MEXICO CITY — An explosion at the main headquarters of Mexico's state-owned oil company in the capital killed 25 people and injured at least 100 Thursday as it heavily damaged three floors of the building, sending hundreds into the streets and a large plume of smoke over the skyline.
There were reports that people remained trapped in the debris — as many as 30 according to civil protection and local media — from the explosion, which occurred in the basement of an administrative building next to the iconic, 52-story tower of Petroleós Mexicanos, or Pemex.
Ana Vargas Palacio was distraught as she searched for her missing husband, Daniel Garcia Garcia, 36, who works in the building. She last heard from him at 1 p.m.
"I called his phone many times, but a young man answered and told me he found the phone in the debris," Vargas said.
"We were talking and all of sudden we heard an explosion with white smoke and glass falling from the windows," said Maria Concepcion Andrade, 42, who lives near the Pemex building. "People started running from the building covered in dust. A lot of pieces were flying."
There was no immediate cause given for the blast, which came at 3:55 p.m. local time, the end of the Mexican lunch break when hundreds of people would have been moving about the complex. But in a Tweet, Pemex said it had evacuated the building as a precautionary measure because of a problem with the electrical system. The company later tweeted that experts were analyzing the explosion and any reports of a cause were speculation.
"It was an explosion, a shock, the lights went out and suddenly there was a lot of debris," employee Cristian Obele told Milenio television, adding that he had been injured in the leg. "Co-workers helped us get out of the building."
Interior Secretary Miguel Osorio Chong initially told Foro TV that 13 people had died at the site, another perished at a hospital, and "more than 80 persons are injured up to this point."
"The priority at this time is to attend to the injured and ensure the physical safety of those who work there," President Enrique Peña Nieto said on his Twitter account.
As darkness fell, search teams were pulling people from the complex. Shattered glass littered streets. Sirens from ambulances wailed throughout the streets surrounding the complex and helicopters hovered overhead.
Police landed four rescue helicopters to remove the dead or injured. About a dozen tow trucks were furiously moving cars to make more landing room for the helicopters.
Streets surrounding the building were closed as evacuees wandered around, and rescue crews put the injured into ambulances.
High-ranking government officials flooded the scene, a sign of the importance to Mexico of Pemex, which provided 34 percent of total government revenues in 2011, according to estimates by the U.S. Energy Department's Energy Information Administration.
Peña Nieto offered his condolences via Twitter, saying, "I deeply lament the deaths of our fellow Pemex workers."
Pemex is on the cusp of major changes opposed by its muscular labor union.
Peña Nieto, who came to office Dec. 1, pledges to reform the energy sector and open oil exploration and production to some forms of foreign investment but without privatizing the state behemoth.
Information from McClatchy Newspapers and the Associated Press was used in this report.