Death toll in Mexico's Pemex gas plant explosion rises to 13

COATZACOALCOS, Mexico, April 21 (UPI) -- The number of casualties from the Pemex gas plant explosion in Mexico has risen to 13, with more than 100 injured.

The cause of the explosion is under investigation. The incident occurred in the southern Mexican city of Coatzacoalcos in Veracruz state at a Petróleos Mexicanos, or Pemex, vinyl chloride plant used to make PVC pipes and packaging materials.

"We toured the affected area of the complex," Luis Felipe Puente, the national coordinator of civil protection for Mexico's Ministry of Interior, said in a statement. "Unfortunately, we have preliminarily located 13 people dead."

Thick smoke billowed into the air as hundreds nearby were evacuated and schools were closed due to possible toxicity.

Pemex is Mexico's state-run gas supplier. The plant affected by the blast was reportedly managed by sister company Mexichem. Officials said exports would not be affected by the explosion and fire.

The explosion resulted in a fire that was controlled by Wednesday evening. Pemex has been criticized for failing to enforce proper protocols due to a number of hazardous incidents, including an explosion at an oil refinery in November that injured at least three workers and an oil rig fire that killed at least four last April.