NFL star Jovan Belcher had argued with his girlfriend after she came home late from an R&B concert the night before he shot her dead then drove to his stadium and committed suicide in front of his coach and general manager, it has emerged.

The 25-year-old Kansas City Chiefs linebacker fatally shot 22-year-old Kasandra Perkins early on Saturday morning, then killed himself in the presence of staff after first thanking them for everything they had done for him, police said.

The couple lived together and three months ago had a baby together on September 11 – but a friend said they quarrelled frequently, and added that they fought when Perkins arrived home at 1am after attending a performance by Trey Songz.

Authorities did not immediately release a possible motive for the murder-suicide, which stunned the team and came one day before a home game against the Carolina Panthers. The NFL said the game would go on as scheduled.

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Murder-suicide: Kansas City Chiefs linebacker Jovan Belcher, 25, shot and killed his girlfriend and then himself on Saturday morning

Happy family: Jovan Belcher killed his girlfriend Kasandra Perkins before shooting himself at the Kansas City Chiefs’ stadium on Saturday morning

Crime scene: Investigators stand outside an Independence, Mo., house where police say Kansas City Chiefs linebacker Jovan Belcher fatally shot his girlfriend on Saturday morning

Love: On Facebook, a profile for Kasandra Perkins includes pictures of her and Belcher with their three month old baby

Judging from pictures posted on Kasandra’s Facebook page, the young couple had appeared to be happy and in love following the birth of their first child.

‘Jovan and Kasandra always seemed to be in love. In fact, when Kasandra got pregnant, she and Jovan were ecstatic. Ever since the baby was born in September, the two couldn’t have seemed happier together,’ a member of the Perkin’s family told TMZ.

Belcher’s agent Joe Linta told ESPN’s Adam Schefter: ‘I’m in shock. So out of character. He was the last person in the world you would expect to do this.’

‘Jovan was a happy, proud father, with pictures of his baby on his Facebook page,’ Linta told SI.com‘s Peter King in a phone call on Saturday afternoon. ‘This is shocking. Something went crazy wrong, and we’ll probably never know what it is.’

‘Never until four hours ago did I think Jovan was anything but a model citizen,’ Linta told King.

‘He came to my youth clinics in the offseason and worked with kids. He was a gracious, unselfish, hard-working, dedicated kid — very, very caring of some of the underprivileged kids who came to the clinics. I saw him in a real positive way.

‘I never take on anyone as a client I wouldn’t be proud to take home and spend time with my wife and kids. Jovan was one of those type of people.

‘There’s no word for this other than shocking. That’s all I can think of.’

Belcher was a 25-year-old native of West Babylon, N.Y., on Long Island, played college ball at Maine. He had played all four of his NFL seasons for the Chiefs and played in every game each year, including the 11 so far this season. His 2012 salary was $1,927,000, four times what he had earned for the previous year.

Before turning the gun on himself, Belcher thanked Chiefs general manager Scott Pioli and Romeo Crennel for all they had done for him, police spokesman Darin Snapp said.

Belcher’s mother had recently moved in with the couple, possibly to help with the baby, at their residence in Independence, Missouri about five miles away from the Arrowhead complex.

She called police just before 8 a.m. to report Perkins had been shot multiple times. Perkins was transported to The University of Kansas hospital, where she died a short time later.

Video: Kansas City football player shoots his girlfriend dead and then kills himself

Jovan Belcher #59 stretches before a game against the Oakland Raiders at Arrowhead Stadium in 2009

Kasandra Perkins’ Facebook profile includes pictures of her with Belcher and their young baby

Jovan Belcher pictured changing his young child’s diaper

‘When we arrived, a lady informed us that her daughter had been shot multiple times by her boyfriend, by the daughter’s boyfriend,’ Snapp said. ‘She identified him as a Chiefs player.’

Snapp told KCTV5 that a call was then received from the Chiefs’ practice facility.

‘The description matched the suspect description from that other address. We kind of knew what we were dealing with,’ he said. The player was ‘holding a gun to his head’ as he stood in front of the front doors of the practice facility.

‘And there were Pioli and Crennel and another coach or employee was standing outside and appeared to be talking to him. It appeared they were talking to the suspect,’ Snapp said.

‘The suspect began to walk in the opposite direction of the coaches and the officers and that’s when they heard the gunshot. It appears he took his own life.’

The coaches told police they never felt in any danger, Snapp said.

‘They said the player was actually thanking them for everything they’d done for him,’ he said. ‘They were just talking to him and he was thanking them and everything.

‘They said he was not a danger to anyone else,” Snapp said. ‘Belcher thanked them for being a Chief, and that’s when he walked away.’

Outside Belcher’s family home in West Babylon, Long Island, family and friends gathered on Saturday afternoon to toast their deceased friends life.

They have created a shrine to the football player on Matthews Avenue complete with Chiefs jerseys and flags from the University of Maine.

Ruben Marshall, a family friend who said he was Belcher’s Police Athletic League coach growing up, told Newsday Belcher was a ‘loving father and family man.’

‘I couldn’t believe it,’ he said upon hearing the news Saturday morning. ‘I didn’t want to believe it,’ Marshall, 42, said as he stood outside the home.

‘He was a good person,” Marshall said. ‘Somebody you’d want to be around as a role model.’

Originally from Texas, Kasandra Perkins had moved to Missouri to be with Belcher

Upon arriving at the Arrowhead Stadium complex, police witnessed a black male in a car with a handgun to his head talking to two Chiefs officials

Before killing himself, Belcher thanked Kansas City Chiefs coach Romeo Crennel for everything he had done for him

Shooting: Arrowhead Stadium is home of the Kansas City Chiefs, Kansas City

Belcher had been the Chiefs starting inside linebacker for the last two seasons after going undrafted in 2009

‘The entire Chiefs family is deeply saddened by today’s events, and our collective hearts are heavy with sympathy, thoughts and prayers for the families and friends affected by this unthinkable tragedy,’ Chiefs chairman Clark Hunt said in a statement.

‘We sincerely appreciate the expressions of sympathy and support we have received from so many in the Kansas City and NFL communities, and ask for continued prayers for the loved ones of those impacted,’ Hunt said. ‘We will continue to fully cooperate with the authorities and work to ensure that the appropriate counseling resources are available to all members of the organization.’

The NFL released a statement that also expressed sympathy and said, ‘we have connected the Chiefs with our national team of professional counselors to support both the team and the families of those affected. We will continue to provide assistance in any way that we can.’

Kansas City Mayor Sly James went to Arrowhead and met with Pioli afterward, according to the Kansas City Star.

‘Think about your worst nightmare and multiply it by five,’ James was quoted as saying.

‘This is part of the tragedy of urban living in this country,’ Mayor James told reporters outside the practice facility.

‘Handguns all over the place, people blowing themselves away, and others. At some point we have to get a handle on this kind of stuff. We are not doing a good job of it.’

Belcher is the second Kansas City Chiefs employee to be involved in a murder-suicide in the last four months. On Labor Day Luis Angel Roberson Rodriquez, who worked in the Chiefs stadium operations department, killed himself after shooting his girlfriend Jamie Kristine Kimble near the Tampa International Airport.

The Kansas City Chiefs home game against the Carolina Panthers is scheduled to go ahead on Sunday

The body of Belcher’s girlfriend was taken to The University of Kansas Hospital

The season has been a massive disappointment for the Chiefs, who were expected to contend for the AFC West title.

But they’re just 1-10 and mired in an eight-game losing streak that has been marked by devastating injuries and fan upheaval, with constant calls the past few weeks for general manager Scott Pioli and coach Romeo Crennel to be fired.

The Chiefs have been ravaged by injuries, led the league in turnovers, can’t settle on a quarterback and are dealing with a full-fledged fan rebellion. The Twitter account for a fan group known as “Save Our Chiefs” recently surpassed 80,000 followers, about 17,000 more than the announced crowd at a recent game.

Things have been so bad this season that Crennel fired himself as defensive coordinator.