TOLUCA, Mexico — A pipeline explosion Sunday that injured seven people and sent flames and smoke shooting hundreds of feet into the air in central Mexico was caused by illegal tapping, Mexico's state-owned oil company said.

The pre-dawn explosion in a farm field injured four police officers and three firefighters among those called to the scene by a report of an oil leak, the state prosecutor's office said.

Petroleos Mexicanos, or Pemex, issued a statement on its Twitter account blaming the blast on an attempt to steal oil with an illicit tap. The supply of crude oil through the pipeline was immediately suspended, it said.

The explosion in Tonanitla in central Mexico state did not threaten any of the area's communities, Mexico state Gov. Eruviel Avila said via Twitter.

There were no evacuations.

An oil leak was first reported about 3:35 a.m. and the explosion occurred at 4 a.m., said Francisco Ventura of the Tecamac municipal police.

Officials reported the fire under control about four hours later.

Illegal tapping is a consistent and serious problem for Pemex, which has seen roughly 20 percent annual increases in thefts of crude oil, gasoline and diesel in recent years, according to Pemex reports and officials. One attempted theft caused an explosion that killed 29 people in December 2010.

Energy Secretary Pedro Joaquin Coldwell, in a widely reported Senate interview in April, said such thefts cost the company about $5 billion a year.