Buildings in Los Angeles and San Diego were said to have swayed from the impact, and in Los Angeles, the fire department was carrying out safety checks on transportation infrastructure, large public venues, apartment buildings and power lines from the ground and air.

The California Earthquake Authority estimated that about 100,000 of its policyholders in Southern California may have felt shaking from the 7.2-magnitude event.

Glenn Pomeroy, CEA chief executive officer, said his agency "will be working closely with our participating insurance companies to promptly process any claims under CEA policies. We are fully prepared and funded to cover all eligible claims."

"This serves as a reminder of the earthquake risk that Californians face every day," Mr. Pomeroy commented. "California is home to about two-thirds of the nation's earthquake risk, with about 2,000 known faults throughout the state, yet only 12 percent of its homeowners with a fire policy also buy earthquake insurance."

The earthquake was also reported to have been felt in Phoenix, Las Vegas and Yuma, Ariz. There were some power outages reported in Southern California, including a power outage that affected more than 600 customers in San Diego County.

Risk Management Solutions catastrophe modeling firm in Newark, Calif. said damage reports from Calexico on the U.S. side of the border mostly described damage to buildings facades, shattered windows, fallen brick and plaster from structures and some contents damage in that city of 36,000.

Badly damaged roads, cracked buildings and downed power lines were reported in cities near the epicenter, in Mexico Guy Carpenter said.

According to an estimate from the U.S. Geological Survey, almost 900,000 people live in areas impacted by a Modified Mercalli Intensity of VII or higher, equivalent to very strong shaking with the potential for moderate to heavy damage.

A majority of this number includes 597,000 people living in the city of Mexicali. About 5,000 people in the city of Progreso experienced an intensity of VIII, equivalent to severe shaking with the potential for heavy damage.

Mexicali, Baja California's capital with a population of 900,000, is located near the epicenter and received the most damage from the earthquake, said Guy Carpenter. There were two fatalities in Mexicali and more than 100 people were injured. The regional government declared a state of emergency for Mexicali.

The governor of the Mexican state of Baja California requested a natural disaster declaration from the federal government.

Mexicali officials said the entire city lost power and telephone services were disrupted in the aftermath of the quake. The civil defense director said there has been at least one building collapse, with other public and private buildings damaged.

The Cat-I report said the chief of the Mexican National Seismological Service cited improved building construction codes as a factor that helped mitigate the amount of serious damage.

USGS estimated that over 20 million people would have felt the earthquake and predicted that aftershocks would be felt over a wide area during the days to come.