A major earthquake struck southwestern Mexico on Tuesday, frightening residents and shaking buildings as far as the capital, though authorities said there were no initial reports of serious damage.

The U.S. Geological Survey said the quake was 7.6 on the Richter scale and located the epicenter of the quake at 15 miles (25 km) east of Ometepec in Guerrero state, near the Pacific Coast resort of Acapulco.

Mexican reports put the strength lower, and residents of Acapulco told Reuters the quake did not appear too violent.

Mexican President Felipe Calderon said on his twitter account there were no reports of serious damage from the quake.

The Pacific Tsunami Warning Center said the inland earthquake would not generate a destructive widespread tsunami, but there was the possibility of some local tsunami effects.

The quake was felt strongly in Mexico City where buildings shook and office employees fled into the street, according to a Reuters witnesses. Cell phone lines were down and traffic snarled in the capital moments after the quake.

"I swear I never felt one so strong, I thought the building was going to collapse," said Sebastian Herrera, 42, a businessman from a neighborhood hit hard in Mexico's devastating 1985 earthquake, which killed thousands.

The quake was felt as far away as Guatemala City. No damage was reported in the southern state of Oaxaca, near where the quake hit, according to local television.

(Reporting by Patrick Rucker; Editing by Anthony Boadle)