The rapper known as Takeoff, a subtle vocal technician and one-third of the chart-topping group Migos, whose singsong flow helped define Atlanta’s ever-evolving, influential rap sound, was shot and killed overnight outside a Houston bowling alley, the authorities said. He was 28. Chief Troy Finner of the Houston Police Department confirmed the rapper’s death at a news conference on Tuesday afternoon. A 24-year-old woman and a 23-year-old man were taken to local hospitals with non-life-threatening injuries, the police said. The police said the shooting occurred after a private party had ended at 810 Billiards & Bowling, as a large group of about 40 people gathered near the front door on the third level. An argument ensued and shots were fired from at least two weapons, they said, leading to many people fleeing. “We have no reason to believe that he was involved in anything criminal at the time,” Chief Finner said of Takeoff. No suspects have been arrested, the authorities said, and they requested that any witnesses who left the scene come forward with additional information. “Sometimes the hip-hop community gets a bad name,” Chief Finner said. “I’m calling up on everybody — our hip-hop artists in Houston and around the nation — we’ve got to police ourselves. There are so many talented individuals, men and women, in that community, who again I love and I respect, and we all need to stand together and make sure no one tears down that industry.”