LOS ANGELES, California (AP) -- A moderate earthquake rocked Baja California in Mexico, shutting down factories near the U.S. border and leaving about 400,000 people without power, authorities said Saturday. No major damage or injuries were immediately reported.
The quake that struck around 11:15 p.m. Friday had a preliminary magnitude of 5.4, said Jessica Sigala, a geophysicist with the U.S. Geological Survey in Golden, Colorado. It was centered 16 miles southeast of the border town of Mexicali and about 100 miles east of Tijuana.
"It has been felt pretty widely in Southern California, southwestern Arizona and probably northern Mexico," Sigala said.
It was followed by at least 15 aftershocks, including four with preliminary magnitudes of 3.8, 3.6, 3.5 and 3.0.
The quake left about 400,000 people without electricity and 1.2 million without cellular telephone service, said Fire Capt. Rene Rosado, director of civil defense in Mexicali.
About 80,000 workers were evacuated or were unable to enter factories for Sony Corp., Honeywell International Inc. and other major corporations that typically run 24 hours a day until the buildings could be checked for damage, he said.
Two bridges showed 2- to 3-inch cracks and were closed until engineers could assess their safety, he said.
The Baja peninsula is a geologically active region. In 2006, a magnitude 5.4 temblor struck the Mexicali area, but there were no injuries or damage. E-mail to a friend
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A moderate earthquake struck Baja California near the Mexico-United States Border  at around 8:15 p.m. () February 8. 

With a  of 5.1, the quake's center was reported to have been between the towns of Mexicali and . No injuries or damage was reported.

Director of civil defense in Mexicali, Fire Capt. Rene Rosado, said several factories have been cleared of workers so that engineers might access possible damage to the structures. Another two bridges have been closed so that cracks could be examined. 400,000 people have been left without electricity, and 1.2 million are unable to use their cell phones. 

The initial quake was followed by around 15 aftershocks and felt, "pretty widely in Southern California, southwestern Arizona and probably northern Mexico," said Jessica Sigala, a geophysicist with the United States Geological Survey (USGS).