Summary The death toll in blast at the Mexico's state-owned oil company has reached 32.
Rescuers dug through mounds of rubble for survivors on Friday after 32 people were killed in a mysterious explosion at the headquarters of Mexico s state-owned oil giant Pemex.
Hundreds of firefighters, police and soldiers aided by dogs have toiled since the blast ripped through an annex of the 54-floor tower on Thursday, injuring 121 people and leaving concrete, computers and office furniture strewn on the ground.
Pemex director general Emilio Lozoya Austin said 20 women and 12 men died in the incident, while 52 more people remain hospitalized. The Mexican Congress held a minute of silence.
As experts investigated the tragedy, Lozoya Austin refused to answer questions about whether an attack was to blame, saying "we won t speculate, we won t get ahead of ourselves."
A civil protection spokesman told AFP Thursday that witnesses had reported a gas build-up in an electricity supply room, but it was unclear whether it was the source of the disaster.
The blast erupted amid a debate over plans by President Enrique Pena Nieto to modernize Pemex and attract more outside investments to the state monopoly, which has suffered deadly industrial accidents as recently as last year.
Officials said the blast will not interrupt production at Pemex, the world s fourth-largest crude producer with an output around 2.5 million barrels per day.
Survivors described an earthquake-like rumble that shook the floor and shattered windows.
The blast heavily damaged the ground floor and mezzanine of the annex, and witnesses said a roof connecting the annex to the tower collapsed.
Mexican Red Cross national coordinator Isaac Oxenhaut said rescuers will scour the site "centimeter by centimeter until we are absolutely sure that no one is in there."
The area is "dangerous to work in," he said, adding that the search could be completed by the end of the day.
Thousands of people work in the Pemex complex, but officials said the area hit by the blast has four levels and housed 200 to 250 employees.
