A quake measuring 7.2 on the Richter scale has rocked buildings all over northwest Mexico and southern California.
Residents said they felt rooms shake and cars jolt after the tremor struck across the Mexican border, some 170 kilometres from Tijuana in the region of Baja California.
US authorities said it was the biggest to hit the area since 1992.
Aftershocks were felt from San Diego to Los Angeles and even as far as Phoenix, Arizona.
The Reuters news agency reported that one person died when a house collapsed in the city of Mexcali.
Mexican officials said some power and phones lines had been cut off, while a highway between Tijuana and Mexcali had been damaged.
Rescue teams with sniffer dogs have been sent out to the worst affected areas.