A gunman opened fire at a crowd of children and adults at a South Los Angeles bus stop just after schools let out Wednesday afternoon, wounding eight, Los Angeles police said.

The incident happened about 3:15 p.m. at the intersection of Central and Vernon avenues, a zone known for its gang violence, Lt. Ruben de la Torre of the Los Angeles Police Department said, according to the Associated Press.

Three girls, ages 10, 11, and 12 and a 49-year-old woman were critically wounded, but were expected to recover. A 12-year-old girl, a 14-year-old boy and two men, ages 48 and 68, had minor injuries. Two of the victims ran away and were found injured outside a nearby middle school, police Officer Sara Faden said.

“Now all of them are stable and expected to recover from their wounds,” De La Torre said, quoted by the same source.

Streets near to the place of the incident, which included a strip mall and a Jack In the Box restaurant were shut down, with numerous police officers investigating in the crime.

Ezequiel Cornejo, 23, a tire mechanic, said he heard about 10 gunshots, probably from a handgun. “After that I saw a little girl running, she was running back to the school, she was holding her arm,” he told AP.

Police were not sure what led to the shooting. They were investigating various scenarios, questioning people who witnessed the whole incident. Some of them said that a gunman stepped off a bus and started firing at the crowd. Others said they saw two men arguing in the Jack In the Box behind the bus stop. One of them left the restaurant, and when the other one stepped out the first man fired at him.

Authorities were searching for the gunman, described as an African-American male aged 20 to 25, about 5-foot-7, 160 pounds, with braided hair, wearing a white T-shirt and blue jeans.