Police were questioning three people and more suspects were being sought early Monday after a shooting that left two officers with minor injuries in South Los Angeles, authorities said.

The officers were in plain clothes and driving near an intersection Sunday evening when someone opened fire, LAPD Detective Meghan Aguilar said. The officers returned fire, and several bystanders scattered from the scene in the neighborhood known for gang violence and drug sales, she said.

It was unclear if the officers suffered gunshot wounds or were struck by shrapnel or glass. They were treated at the scene.

Junior Moore, 54, said he was eating at a fast-food restaurant when the gunfire erupted about 5:45 p.m.

"I heard, like, 20 shots and then a bunch of police sirens," Moore told the Los Angeles Times (http://lat.ms/19rFLoq).

Three people were being questioned, but no arrests have been made, Officer Rosario Herrera said.

Investigators were trying to determine whether the officers were targeted.

Police canvassed a wide area through the night, and several blocks remained shut down early Monday. Officers were combing the area for shell casings and potential witnesses.

Dozens of officers, police dogs, a helicopter crew and SWAT vehicles participated in the search.