Manhunt underway for suspect who fatally shot Migos rapper Takeoff

As tributes pour in for Migos rapper Takeoff, who was shot and killed in downtown Houston on Tuesday, police are urging anyone with information about his killing to come forward.

"Somebody knows exactly who it was and I'm pretty confident that somebody's gonna step up," Houston Police Chief Troy Finner told reporters on Tuesday.

Takeoff, whose real name is Kirshnik Khari Ball, was 28. According to the medical examiner's report, the cause of death was "penetrating gunshot wounds of head and torso into arm."

The rapper was a member of the hip-hop trio Migos, a Grammy-nominated group based in Atlanta. Takeoff's uncle Quavo, who was present when the shooting took place, and his cousin Offset were also part of the trio.

Takeoff and Quavo were attending a private event at the 810 Billiards & Bowling in downtown Houston, police said. Multiple shell casings were found on the third level of the venue, according to police.

"After [the event] ended, there was a large group of people who gathered at the front door area just outside of the building and it led to an argument where the shooting took place from the disagreement," Sgt. Michael Arrington of the Houston Police Department told reporters on Tuesday.

Finner said the event was attended by about 40 other people and urged witnesses to "step up" and share cellphone videos of the incident and any other information about a potential suspect or suspects.

"I just want to say something to our city. It's Houston and every brother and sister in the neighborhoods, I'm calling you to action, to step up. There were 40 people at least at this event and people left possibly out of fear," Finner said. "I ask you one thing and I want this to resonate with everybody. What if it was your brother? What if it is your son? You want somebody to step up? So please step up, get the information to us so we can bring some closure to this family."

Finner said that while hip-hop sometimes gets a "bad name," there are many great people in the hip-hop community and he plans on meeting with artists "as early as next week" to "see how we can taper things down."

The rapper's labels, Quality Control Music and Motown Records, released statements mourning the loss of Takeoff.

"Senseless violence and stray bullet has taken another life from this world and we are devastated," Quality Control Music said.

Asked about reports that the rapper was not involved in the argument but was killed by a stray bullet, Finner said police are still in the "early stages" of the investigation. After talking with people who were present, "we have no reason to believe that he was involved in anything criminal at the time," he added.

"Based on what people say about him, he's well respected, nonviolent. I would not expect him to be involved," Finner said.

Arrington told reporters that officers were called at about 2:30 a.m. to the 1200 block of San Jacinto, where they found a Black man in his late 20s dead on the scene.

Police confirmed on Tuesday afternoon that the man found dead on the scene was Takeoff.

Arrington said two other victims - a 23 year-old male and 24 year-old female - suffered non-life threatening injuries and transported themselves to the hospital.

Police urged anyone with information about the shooting to contact the HPD homicide unit at 713-318-3600.

ABC News' Jennifer Watts contributed to this report.