MEXICO CITY, Sept. 8 (Xinhua) -- At least nine people were killed in a powerful earthquake measuring 8.0 on the Richter scale that struck off Mexico's southern coast late Thursday, local authorities said.

Seven people were killed when homes collapsed in the state of Chiapas, confirmed Jose Garcia, an official from the state's civil protection department.

Another two were killed in the neighboring state of Tabasco, according to local authorities.

The epicenter of the quake is 96 km southwest of the town of Pijijiapan in Chiapas, at a depth of 33 km, the United States Geological Survey (USGS) said.

The shock was also felt in the capital of Mexico City, where many people ran out of buildings onto the streets.

People said the shock lasted for about dozens of seconds and the windows and beds in some building were shaking when the quake occurred.

Mexico City mayor Miguel Angel Mancera told local media that there were electrical outages but no reports of collapsed buildings or deaths.

Firefighters and police have been on inspection tours around the capital to check for any damage caused by the quake.

The southern Mexican state of Chiapas bordering Guatemala suffered severer damage than the capital according to pictures posted by Twitter users showing some houses collapsed or cracked.

A picture posted by "Periodico Coleccion" on Twitter shows the severely damaged roof of a shopping mall in Chiapas, with part of it falling on the ground.

Mexican President Enrique Pena Nieto said the national emergency-response system has been activated and instructions have been issued to local governments to undertake monitoring and rescue operations.

The earthquake is the strongest in Mexico since 1985 when a magnitude-8.0 quake hit Mexico City that killed thousands of people and destroyed large parts of the capital.