NASHVILLE (AP) - Nashville police are increasing security at a downtown bus terminal in the aftermath of shootings that wounded four teenage boys.

Javious Chatman, 18, was seriously injured in Monday's shooting, but his condition had improved to stable by Tuesday, said police spokesman Don Aaron. Three boys, two 16 and one 17, were also shot and sustained non-life-threatening injuries, police said in a news release.

The Music City Central MTA bus terminal was crowded when shots were fired near an upper level escalator around 3:30 p.m., the release said, and people began running at the sound of gunfire.

The terminal is a central transfer station for schoolchildren and other passengers and an estimated 4,000 children travel through it every day, going back and forth to school, jobs and extracurricular activities, said Patricia Harris-Morehead, a spokeswoman for the Nashville MTA. She said the terminal has always been very secure and saf e.

The terminal has 44 surveillance cameras, she said, and normally has four to five commissioned police officers and three additional security officials. The school system will occasionally provide additional security, she said.

"Music City Central is one of the safest facilities in the Metro Nashville downtown area because of the partnership that we have with the Metro Police Department and the Metro Schools department," Harris-Morehead said.

The shooting was "seemingly targeted," Aaron said, and police think the three teens who suffered less serious injuries were hit by stray rounds.

Two people who were detained following the incident have since been released, and investigators are looking at video surveillance and pursing other leads to determine the shooter.