6.4-magnitude earthquake hits Southern California — strongest in 20 years

A 6.4-magnitude earthquake was reported in Southern California on Thursday just after 10:30 a.m. local time near the city of Ridgecrest, about 320 kilometres northeast of Los Angeles — the strongest to hit the state in 20 years.

According to European quake agency EMSC, the earthquake was felt in an area inhabited by some 20 million people.

WATCH: People in Los Angeles say earthquake was ‘rolling’ and ‘weird’ experience

1:48 People in Los Angeles say earthquake was ‘rolling’ and ‘weird’ experience

Multiple injuries and two house fires reported in the town of 28,000, according to Kern County Fire Chief David Witt.

He said 15 patients were evacuated from the Ridgecrest Regional Hospital as a precaution and out of concern for aftershocks.

U.S. President Donald Trump said on Twitter he was fully briefed on the earthquake on that it “all seems to be very much under control.”

The Los Angeles Fire Department tweeted about the incident minutes after it occurred, calling it a “significant earthquake.” The temblor was felt as far as L.A. and was quickly followed by several smaller aftershocks in the area.

WATCH: Likelihood of another earthquake in southern California ‘unknown’

0:51 Likelihood of another earthquake in southern California ‘unknown’

Kern County Fire Department Battalion Chief Jason Schillinger said 87 aftershocks occured in the Ridgecrest area, and it is “unknown” whether another earthquake will occur.

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The aftershocks included a 4.5 magnitude temblor, according to the United States Geological Survey.

Lucy Jones, a seismologist with the California Institute of Technology’s seismology lab, said the quake was the strongest since a 7.1 earthquake struck the area on October 16, 1999.

WATCH: More than 87 aftershocks since southern California rocked by earthquake

0:33 More than 87 aftershocks since southern California rocked by earthquake

“This has been an extremely quiet abnormal time,” Jones said. “This type of earthquake is much more normal … The long term average is probably once every five or 10 years somewhere in Southern California.”

Jones said she wouldn’t be surprised if a magnitude 5 quake hit among the aftershocks, but they were located in a remote, sparsely populated area.

“This is an isolated enough location that that’s going to greatly reduce the damage,” she said.

Gov. Gavin Newsom declared a state of emergency for Kern County, which means that the state will help the county and its municipalities with emergency aid and recovery efforts.

The Los Angeles Police Department said on Twitter that the quake is not suspected to have resulted in any damage in the city itself.

It’s unclear exactly how many people were affected by the earthquake overall and what the damage may be.

The Los Angeles International Airport tweeted that its operations “remain normal” after the quake and that no damage was found on site.

The U.S. National Tsunami Warning Center tweeted that a tsunami is not expected to follow the quake.

Jones told CNN the area would, however, be hit by more aftershocks in the coming days.

WATCH: USGS provides details about southern California earthquake

2:38 USGS provides details about southern California earthquake

California is on the so-called Pacific Ring of Fire and is prone to earthquakes.

Thursday’s quake is the largest in Southern California since the 1994 6.6-magnitude Northridge earthquake, which was centred in a heavily populated area of L.A.

—With files from Reuters and the Associated Press