Several people were injured and hundreds of others had to be evacuated Monday when a pipeline belonging to state-owned oil giant Petroleos Mexicanos, or Pemex, exploded as it was being tapped illegally in Acolman, a city in Mexico state, officials said.

The incident occurred around 1:30 a.m. and "was caused by an illicit tap" on a pipeline, Pemex said.

"Specialized personnel from Pemex Gas y Petroquimica Basica put a fire caused by a clandestine tap under control on the 24-inch Cactus-Guadalajara pipeline in the city of Acolman," the state-owned company said in a statement.

The flow of fuel through the pipeline was shut off after the explosion and residents are not in danger, Pemex said.

Mexico state emergency management officials did not provide figures on the number of people injured in the blast or evacuation numbers because the situation is being handled by federal officials.

Mexico state surrounds the Federal District and forms part of the Mexico City metropolitan area.

The explosion injured four to seven people and forced the evacuation of between 150 and 800 people from the Radio Faro neighborhood, media reports said, citing officials in Acolman and Tezoyucan.

Firefighters from the cities of Acolman, Tezoyuca and Ecatepec, as well as from the Mexico state Public Safety Secretariat, and emergency management office personnel are in the blast zone, which was cordoned off.

"The legal department of this state-owned company has been notified of the incident and will file a complaint with federal prosecutors to initiate an investigation and determine who is responsible," Pemex said.

Pemex expects 2013 to be a record year in terms of stolen fuel, with losses totaling some 7.06 billion pesos ($585 million).

Theft of fuel from Pemex pipelines, known in Mexico as "milking," is common, with both individuals and gangs involved in the illegal activity. EFE