At least 14 people died Thursday in an explosion in the centre of Mexico City at the headquarters of the state oil company, Petroleos Mexicanos (Pemex), dpa reported quoting as the company saying.
One hundred people were injured in the blast, according to Interior Minister Osorio Chong, who was quoted by the newspaper El Universal online.
About 30 people were believed to be buried in the rubble. The cause of the explosion in the basement of the building was not known. Some witnesses spoke of two blasts.
Sources in Pemex said the air-conditioning system of the building was overheated. The president of the union of oil workers, Moises Flores, spoke of negligence in maintaining the heating and air-conditioning system.
The 211-metre-high building was evacuated, and the streets around the building were blocked off. Four of the high rise's 50 storeys were badly damaged.
The Pemex Tower, the city's second-highest building, was constructed in 1984 and was considered secure from earthquakes.