SANTA MONICA, Calif. — A rolling 6.4-magnitude earthquake hit a remote area of Southern California between Los Angeles and Las Vegas on Thursday, the most powerful tremor to shake that region in two decades, according to the United States Geological Survey.

The quake, which struck shortly after 1 p.m. Eastern, caused dozens of aftershocks, about two dozen fire and medical incidents and the evacuation of several apartment buildings. But it appeared that no one was seriously injured in the temblor, the authorities told reporters at a news conference.

David Witt, the Kern County fire chief, said most emergency calls were coming from Ridgecrest, a small desert city of about 30,000 residents that was closest to the epicenter. Among them were minor injuries, a couple of house fires, downed power lines and some gas leaks. Watch it here.