A car has slammed into a tree in the 2800 block of Glenoaks Boulevard in Glendale after what may have been a street race, police said.
Witnesses reported the crash near Scholl Canyon at 1:37 p.m., but it was not immediately clear if anyone was hurt.
Officers have detained three people who may have been involved in the crash, police Sgt. Tom Lorenz said.
The occupants of the vehicle reportedly threatened one witness in an attempt to dissuade them from calling police to report the crash, Lorenz added.
A second car may have been involved.
Glendale firefighters and paramedics are at the scene.
[Update 3:15 p.m.: The crash involved two cars, a small Infiniti sedan and a Toyota Camry. Police said some of the occupants may have sustained minor injuries, possibly from deploying airbags.]