LOS ANGELES (AP) — The Latest on Southern California's strongest earthquake in 20 years (all times local):

7:05 a.m.

A vigorous aftershock sequence is following the strongest earthquake to hit Southern California in 20 years.

A magnitude 5.4 quake at 4:07 a.m. Friday is so far the strongest aftershock of Thursday's magnitude 6.4 jolt, and was felt widely.

Seismologists had said there was an 80% probability of an aftershock of that strength.

Thursday's big quake struck in the Mojave Desert, about 150 miles (240 kilometers) northeast of Los Angeles, near the town of Ridgecrest, which suffered damage to buildings and roads.

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9 p.m.

The strongest earthquake in 20 years shook a large swath of Southern California and parts of Nevada on the July 4th holiday, rattling nerves and causing injuries and damage in a town near the epicenter, followed by a swarm of ongoing aftershocks.

The 6.4 magnitude quake struck at 10:33 a.m. Thursday in the Mojave Desert, about 150 miles (240 kilometers) northeast of Los Angeles, near the town of Ridgecrest, California.

Kern County Fire Chief David Witt says multiple injuries and two house fires were reported in the town of 28,000. Emergency crews were also dealing with small vegetation fires, gas leaks and reports of cracked roads.

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