Danny Lopez was taken into custody Sunday after being tackled by family members, the Los Angeles Times reported.
Police Detective Gus Villanueva said Lopez "was upset about a friend or family member who passed away."
The city police helicopter came under fire about 6 a.m. when the pilot responded to a report of gunshots in Van Nuys. The chopper sustained a ruptured fuel tank and the pilot made an emergency landing.
A semiautomatic rifle was recovered, police said.
There were reports of a second gunman but police said they didn't find one despite hours of searching.
"This situation could have easily turned tragic and we were just fortunate," Assistant Chief Earl Paysinger said. "It's ironic that it happened on Easter Sunday. Someone divine was watching over us."