A strong earthquake has struck central Mexico, killing more than 140 people and toppling dozens of buildings in the capital, Mexico City, reported BBC.

The BBC quoting President Enrique Peña Nieto said more than 20 children and two adults had been found dead at the collapsed Enrique Rebsamen school in Mexico City's southern Coapa district. He said another 30 children and eight adults were missing.

At least 149 people have died across the country, a civil protection agency spokesman said.

Likewise, at least 55 people were killed in Morelos state, south of the capital, and 32 reported killed in Puebla state. Forty-nine are confirmed dead in Mexico City, with another 10 in Mexico State, and three dead in Guerrero. A six-storey blocks of flats, a supermarket and a factory were also said to be among the collapsed buildings in the city.

The 7.1 magnitude quake also caused major damage in neighbouring states. The prolonged tremor hit at 13:14 local time (18:14 GMT) and sent thousands of residents into the streets. The epicentre of the latest quake was near Atencingo in Puebla state, about 120km (75 miles) from Mexico City, with a depth of 51km, the US Geological Survey said.

The tremor struck while many people took part in an earthquake drill exactly 32 years after a quake killed thousands in Mexico City. The earthquake drill was being held in Mexico City on the 32nd anniversary of a quake that killed up to 10,000 people. Earthquake alarms did sound, correspondents say, but some residents apparently thought they were part of the day of drills.

The country is prone to earthquakes and earlier this month an 8.1 magnitude tremor in the south left at least 90 dead. Mexico City is one of the most densely populated cities in the world, with more than 20 million people living in the metropolitan area.

As per the report, about two million people in the capital were without electricity and phone lines were down. Officials also warned residents not to smoke on the streets as gas mains could have been ruptured.

Mexico City Mayor Miguel Angel Mancera told TV network Televisa that rescue services were dealing with collapsed or badly damaged buildings at 44 locations.

In a televised address, the president said an emergency had been declared for the affected areas and the military was being drafted in to help with the response. Across Mexico City, teams of rescue workers and volunteers clawed through the rubble with picks, shovels and their bare hands.