The plant is owned by state-run energy giant Petroleos Mexicanos (Pemex), and is located in Tamaulipas state, Xinhua reported.
The fire, which broke out at 11 a.m., was doused about an hour later, Pemex said in a statement. Dozens of people were injured.
About 700 people were working at the facility when the fire broke out.
Residents living within a five-kilometer radius of the plant were evacuated.