A large number of police and rescue personnel were responding to a Los Angeles supermarket, amid numerous media reports of possible gunshots.
The Los Angeles Police Department tweeted there was an "active incident" at a Trader Joe's in the Silver Lake area.
Calls to the department's public information office were not immediately answered. Reports of gunshots could not immediately be confirmed.
An Associated Press employee who lives in the area reported seeing a crashed car into a utility pole outside the store.
One tweet showed people attempting to exit the Trader Joe's out a window. Other views from TV helicopters showed people leaving through the front door with their hands up.
No further details were immediately available.