Death Toll in Mexico Oil HQ Blast Rises to 32

The death toll in an explosion at the headquarters of Mexico's state-own oil giant Pemex rose to 32 on Friday as rescuers dug through the rubble while the cause of the blast remained a mystery.

Hundreds of firefighters, police and soldiers toiled through the night after the blast ripped through an annex of Pemex's 54-floor tower on Thursday, leaving huge pieces of broken concrete on the ground and injuring 121 people.

Pemex director general Emilio Lozoya Austin said 20 women and 12 men died in the incident, while 52 people remain hospitalized. He said the search for survivors would continue.

Lozoya Austin added that Mexican and foreign experts were investigating what caused the tragedy and that "we won't speculate, we won't get ahead of ourselves."

The blast will not interrupt production at Pemex, the world's fourth-largest crude producer with around 2.5 million barrels per day, he said.

Survivors described an earthquake-like rumble that shook the floor and shattered windows after the blast heavily damaged the annex's ground floor and mezzanine. Witnesses said a roof connecting the annex to the tower collapsed.

The area hit by the blast has four floors and houses 200 to 250 employees, Lozoya Austin said.

The explosion sent shocked employees pouring out of the complex beneath a pillar of black smoke, some carrying wounded people out on office chairs.

"A good part of the rubble was removed and we hope to be able to finish the removal in the morning," a city civil protection spokesman told Agence France Presse, adding that the search focused in the basement.

At least six ambulances were at the scene in case any people were found, while police partially reopened traffic on the heavily-traveled avenue in front of the complex. Officials said 46 people remained hospitalized.

"We were waiting all night to assist in a major emergency that did not materialize because, fortunately, it appears that almost everybody was taken out," a military nurse who refused to give her name told AFP.

Floodlights shined on the rubble and two cranes were brought to help rescuers in hard hats and surgical masks look for survivors. One survivor was found almost six hours after the blast, which took place around 3:40 p.m. (2140 GMT).

A spokesman for the civil protection agency said Thursday that there was an apparent "accumulation of gas" in an electrical supply room, but the exact cause of the blast has yet to be confirmed.

Interior Minister Miguel Angel Osorio Chong warned against any speculation, saying late Thursday that the goal of the probe was to "produce precise, trustworthy and convincing data to find out the origin and cause of the disaster."

Emergency workers with rescue dogs, helicopters and several ambulances were at the scene in the capital -- a city that is equipped to handle earthquakes.

"We had two minutes to leave the building. I was headed to the pharmacy when the windows broke. It was a deafening noise," Astrid Garcia Trevino, who worked in the annex, told AFP. "The floor shook as if it was an earthquake."

Gloria Garcia said her brother Daniel, 35, had called from the building and said he was trying to get out. She hasn't heard from him since.

"We're afraid he might still be in there," she said.

Pemex had indicated before the blast was confirmed that the building was evacuated due to an electrical failure.

President Enrique Pena Nieto took office in December promising to modernize Pemex in order to attract more private investment but he insists that the company will never be privatized.

The company has experienced deadly accidents at its oil and gas facilities in the past. Last year, a huge explosion killed 30 people at a gas plant near the northern city of Reynosa, close to the US border.

The previous worst incident took place in December 2010, when an oil pipeline exploded after it was punctured by thieves in the central town of San Martin Texmelucan, leaving 29 dead and injuring more than 50.

In October 2007, 21 Pemex workers died during a gas leak on an oil platform in the Gulf of Mexico. Most drowned when they jumped into the sea in panic.