By Michael Winter
An explosion at the headquarters complex of the Mexican state oil monopoly killed at least 14 people and injured 80 others Thursday afternoon, the government says.
Interior Minister Miguel Angel Osorio Chong told Mexican television the death toll may rise.
The cause has not been confirmed. Local media reported that machinery exploded in the basement of an administrative center next to the 52-story Pemex tower in Mexico City, the country's second-tallest building.
Three floors of the auxiliary office were heavily damaged. There were unconfirmed reports that up to 30 people may be trapped.
Milenio TV said people were still trapped under the rubble. Hector Serrano, a Mexico City government official, said on his Twitter page that rescue dogs were searching for survivors, Bloomberg News reported.
The blast happened about 3:30 p.m. local time (4:30 p.m. ET) in the B2 building, Pemex said on Twitter. "There are injuries and damage on the ground floor and mezzanine," it wrote.
Before the blast, Pemex -- Petróleos Mexicanos -- announced it had evacuated the building because of electrical problems.
The El Universal newspaper is reporting that an overheated air conditioning unit may have caused the blast.
Interior Department spokesman Eduardo Sanchez confirmed to the Associated Press that the blast occurred in the basement garage of the office tower, where several thousand people work.
AP reports that the blast blew out windows on three floors of the auxiliary building.
"The place shook, we lost power and suddenly there was debris everywhere. Colleagues were helping us out of the building," witness Cristian Obele told Milenio.
One worker on the 10th floor described to NPR "an amazing explosion" and being thrown from his chair.