SAN FRANCISCO (CBS SF/AP) -- A major earthquake measuring 7.4 in magnitude struck along Mexico's west coast off the state of Oaxaca Tuesday, triggering a tsunami warning stretching from Acapulco to the coast of El Salvador and killing at least five people, according to authorities.
Oaxaca Gov. Alejandro Murat said there were rescue crews trying to get to a remote mountain village were some 15 people were reported trapped under rubble.
The quake -- which was originally tagged to 7.7 magnitude -- struck at 8:29 a.m. on the coast southwest of Oaxaca. Almost immediately, the U.S. Tsunami Center issued a warning for coastal communities in Mexico, Guatemala, Honduras and El Salvador.
There was no threat posed to the California coastline.
The temblor struck on a relatively unpopulated area of the Mexican west coast located off the Gulf of Tehuantepec. The nearest village was Santa Maria Zapotitlán located 7 miles away.
But social media was filled with images of toppled store shelved and quake damage in Oaxaca.
Hundreds of miles away in Mexico City, buildings swayed and thousands scrambled into the streets.
Seismic alarms sounded midmorning with enough warning for residents to exit buildings. Power was knocked out to some areas, but there were no immediate reports of damage or injuries.
Helicopters flew over downtown Mexico City and police patrols sounded their sirens.
In Huatulco, a laid-back beach destination known for surfing and small protected coves, the earthquake knocked goods off shelves and some rubble from buildings.
Mari González of the Princess Mayev hotel in Huatulco said staff and guests were able to evacuate the building before the quake, but that 45 minutes after the initial quake they were still outside as strong aftershocks continued.
"It was strong, very strong," she said.
González said there was some visible broken glass and mirrors, but no major damage. The staff was waiting for the aftershocks to dissipate before fully evaluating the property.
Local news media reported damage to some buildings in the state capital, Oaxaca city. State officials said they were looking for damage.
The USGS estimated that some 2 million people felt strong or moderate shaking and another 49 million felt weak or light shaking.
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