Deadly explosion rocks Mexico City skyscraper housing Pemex Guillermo Gutierrez / AP Firefighters and workers dig for survivors after an explosion at the executive tower of Mexico's state-owned oil company PEMEX, in Mexico City, Thursday. By Kari Huus, Staff writer, NBC News An explosion in the Mexico City skyscraper complex housing the headquarters of state oil monopoly Pemex killed 14 and injured at least 80, company and government officials said. There were also reports that as many as 30 people remained trapped in the debris from the blast, but NBC News has not confirmed that information. The explosion took place in the basement garage of the auxiliary building of the complex, next to the company's 52-floor tower located in a busy commercial and residential area, Interior Department spokesman Eduardo Sanchez told reporters. The main floor and the mezzanine of the auxiliary building were heavily damaged, along with windows as far as three floors up. The adjacent Pemex officer tower, where several thousand people work, was evacuated. There was no official explanation for the blast. "An explosion took place in the B2 building of the administrative center," Pemex said on Twitter and photos showed smoke pouring out of the building. "There are injuries and damage on the ground floor and mezzanine," Pemex said, promising further information as it became available. Pemex initially said the building had been evacuated because of a problem with its electricity supply. It then said there had been an explosion, but it did not mention the cause. Television images showed people being evacuated - some on office chairs and gurneys. Emergency crews loaded people on stretchers into helicopters and airlifted out of the area. "The place shook, we lost power and suddenly there was debris everywhere," Cristian Obele told Milenio news network. Colleagues were helping us out of the building. "We were talking and all of sudden we heard an explosion with white smoke and glass falling from the windows," Maria Concepcion Andrade, 42, who lives on the block of Pemex building told The Associated Press. People started running from the building covered in dust. A lot of pieces were flying. Milenio TV via NBC News The scene at Pemex headquarters in Mexico City on Thursday after an explosion. Lines of fire engines rushed to the entrance of the building and emergency workers in high-visibility jackets ferried injured people through paper and debris strewn on the street. The ceiling of the basement was damaged, and the situation at the Pemex tower was dangerous, Reuters said, quoting a spokesman for local emergency services. Reuters and The Associated Press contributed to this report.