The Kansas City Chiefs and the NFL recoiled Saturday from news that a Chiefs linebacker had fatally shot himself outside the team’s practice facility in an alleged murder-suicide involving his 22-year-old girlfriend.

Jovan Belcher, 25, shot Kasandra Perkins multiple times Saturday morning at their Kansas City, Mo., home before driving to the team’s Arrowhead practice facility, Police Capt. David Lindaman told reporters. In the parking lot, Belcher spoke with Chiefs Coach Romeo Crennel and General Manager Scott Pioli and reportedly thanked them for the opportunity to play in the NFL. When police arrived, as Crennel and Pioli looked on, Belcher shot himself in the head, Lindaman said.

Belcher’s suicide and the alleged murder came after an argument with Perkins, the Kansas City Star reported Saturday afternoon.

Hours after the deaths, Belcher’s teammates were wondering how a quiet, overachieving player who went from undrafted free agent to a fixture in the starting lineup could carry through with such acts.

“That’s what hurts you the most,” Chiefs defensive lineman Shaun Smith said in a telephone interview late Saturday afternoon. “That a guy like that would do that.”

Smith, who played with Belcher throughout 2010 and rejoined the team in early November, said Belcher had never displayed signs of anger or a violent temper and hadn’t spoken about problems between him and Perkins. The couple had dated for years and had a 3-month-old daughter.

Smith described Belcher as a happy, playful teammate who was never afraid to snipe back at the gregarious Smith. In fact, Smith said, the teammates walked off the practice field together Friday, with Smith ribbing Belcher about how little he had played a week earlier against the Denver Broncos and quarterback Peyton Manning. The Chiefs had played mostly in a nickel defense, leaving Belcher on the bench, and Smith, normally a backup, on the field. 

“You know, just having fun,” Smith said.

Belcher, a starting inside linebacker the past four seasons, and Perkins reportedly had attended a concert Friday night and argued afterward, continuing the disagreement into Saturday morning. Lindaman told reporters that Belcher shot Perkins around 7:50 a.m., with Perkins’s mother witnessing it. Perkins was pronounced dead later at a hospital. Belcher then went to the team facility, where Chiefs officials tried talking the player out of additional acts of violence.

A police spokesman told Kansas City media that Belcher hadn’t threatened team officials; rather, he thanked Crennel and Pioli.

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

Many of Belcher’s teammates turned to Twitter to express sadness and disbelief.

“Devastated,” tight end Tony Moeaki wrote.

“Forever in our heart!” free safety Kendrick Lewis posted.

The Chiefs are scheduled to play the Carolina Panthers at Arrowhead Stadium on Sunday, and Crennel is expected to coach his team a little more than 24 hours after witnessing a player’s suicide.

Smith said he didn’t disagree with the decision to play. He said he hopes some goodwill comes from it.

“Life still goes on,” he said. “. . . If anything, it’s going to bring guys closer.”

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.”

When Smith arrived Saturday morning at the practice facility for final meetings, a police officer turned him away. Police had set up a barricade, blocking the players’ entrance. Smith said he drove around, then received word to head to Arrowhead Stadium, about a half-mile from the practice facility.

There, Smith said, Crennel addressed the team and told players that Belcher had committed suicide.

“That was it,” Smith said. “Guys shed tears.”

In parts of four NFL seasons, Belcher never missed a game and had no known history of concussions or head injuries. Smith said his teammate showed no signs of depression or emotional imbalance.

“I don’t know what happened,” Smith said. “. . . I just feel so sorry for his mom and also his girlfriend’s mom.”

Smith also played for the Tennessee Titans earlier this season, when wide receiver O.J. Murdock committed suicide.

“I almost think: Who’s next?” Smith said.

Belcher was an all-American wrestler at his high school in West Babylon, N.Y. His college options were limited in wrestling, though, so he turned to football at the University of Maine, where he was a four-year starter and graduated with a degree in child development.

Once a 171-pound wrestler, Belcher built himself into a 235-pound defensive end strong at stopping the run.

He wasn’t drafted but signed with the Chiefs in 2009, eventually working his way up the depth chart. Coaches liked that he used the same attributes that make a good wrestler on the football field: strength, balance and leverage. He started 44 NFL games and tallied 257 tackles.

Three years ago, during his rookie season, he stood at his locker one afternoon and talked about the future, saying, “I always like to think anything is possible.”

Before this season, Belcher signed a one-year, $1.9 million contract to remain with the Chiefs.

As an NFL rookie in 2009, he spoke about learning to harness his natural abilities, and what it took to reach the NFL.

“It’s just you,” he said then. “You don’t have somebody pushing you.”