Police investigate cause of Mexico City office blast that killed 32

Explosion in Petroleos Mexicanos headquarters initially blamed on a gas boiler

An embassy security guard arrives at the Gate 2 of the US embassy just minutes after a suicide bomber has detonated an explosive device at the entrance of the U.S. Embassy (AP)

Police in Mexico City were struggling today to determine the cause of an explosion which killed at least 32 people and injured more than 120 at the headquarters of Petroleos Mexicanos (Pemex), the country’s national oil conglomerate, as rescuers continued to search the rubble for trapped survivors.

The blast happened just before 4pm local time on Thursday, in the basement of an administrative building adjacent to the company’s main office. It tore through the lower floors of the 54-storey skyscraper in the downtown Miguel Hidalgo neighbourhood.

Pemex first announced on Twitter that its HQ had been evacuated due to an electrical failure. When it became clear that an explosion had occurred, early reports blamed a faulty gas boiler. Enrique Peña Nieto, the recently elected Mexican President, visited the scene on Thursday evening. He acknowledged that the cause of the blast was unclear, but pledged that if anyone were found to be responsible, the authorities would, “apply the full weight of the law against them.”

As a precaution, security officials swept Congress in search of explosive devices, but found nothing.

Describing the investigation as “complicated”, the CEO of Pemex Emilio Lozoya said yesterday that 20 women and 12 men had been killed, while 52 of the 121 injured remained in hospital.

“A fatal incident like yesterday’s cannot be explained in two hours; we are working with the best teams in Mexico and from overseas. We will not speculate,” Mr Lozoya told a news conference.

Around 3,500 people were evacuated from the building, Mexico’s second tallest. Some 500 rescue workers searched through the night with dogs, and at least one survivor was found alive in the debris. Shaken Pemex workers suggested the explosion felt like a bomb or an earthquake. Leticia Vigueras, 38, a finance department employee, told The Washington Post that at least one of her co-workers had been killed. “From the magnitude of the damage, it’s hard for me to think that it was an accident,” she said.

Mexico’s state oil monopoly has suffered a series of deadly disasters in recent years. In September 2012, 30 were killed by a fire at a gas distribution hub near the US border. In 2007, 21 workers died when an oil rig collided with a drilling platform in the Gulf of Mexico. The firm has also been targeted by the country’s rampant gangs: in 2010, 28 people died in an explosion in the state of Puebla as a group of criminals attempted to steal oil from a pipeline. According to the Mexican newspaper Milenio, the government has repeatedly denied requests to update Pemex’s disaster-prevention equipment.

The company said its headquarters would be closed until further notice, but its oil production, fuel processing and distribution would continue to operate as normal.