ATLANTA — A shooting at a rap concert in downtown Atlanta that killed two people and wounded two others began when two people climbed onstage between performances, police said.

The two who climbed onto the stage at The Masquerade at Underground Atlanta were shot Sunday night by someone in the crowd who got angry, Atlanta police officer Lisa Bender said.

Two others were wounded, Bender said.

The gunman managed to escape as the crowd fled, Bender told The Atlanta Journal-Constitution. ‘‘The suspected shooter, still armed, was witnessed by unarmed security but was not successfully detained,’’ she said.

One victim died at the scene from a gunshot wound to the chest. The others were taken to a nearby hospital, where a second victim died.

ASSOCIATED PRESS