Police were working to detain a man who had exchanged gunfire with officers while barricaded in an apartment building in Sherman Oaks on Friday.
The incident prompted the evacuation of surrounding residences in the 4700 block of Tyrone Avenue as authorities worked to resolve the situation, said Los Angeles Police Officer Hector Guzman.
Officers first responded to reports of a man with a gun at the location just after 5 p.m. and remained at the active scene after midnight. It was unknown whether the man had threatened anyone, Guzman said.
Officials were initially able to communicate with the suspect, a man in his 20s, both face-to-face and via cellphone.
At some point after that, communication broke down and the suspect fired at officers from inside the apartment building, officials said.
No officers were injured, but it prompted at least one officer to discharge their weapon. Authorities had not yet determined how many shots were fired.
It was not immediately known whether the suspect was struck. He was no longer communicating, but "all indications are that the suspect is alive," Guzman said.
There are no known previous mental evaluation contacts with the suspect, according to Guzman.
The man was believed to be armed and the sole person remaining in the apartment building, which was evacuated along with surrounding complexes. Resources were being provided to the evacuees, who were referred to cooling centers.
SWAT teams, crises negotiators and a mental evaluation unit were also at the scene, which remained active late Friday night.
Riverside Drive and Tyrone Avenue would be closed at least until the situation was resolved, and the public was asked to avoid the area.
KTLA's Matt Phillips contributed to this report.