An explosion at a petrochemical refinery on Mexico's Gulf Coast Monday killed three people and injured 329 others, shaking the ground and rattling windows several miles away, officials said.

The explosion occurred at 8:40 a.m. at the Colorado petrochemical refinery in Pajaritos, about 300 miles east of Mexico City, said Vania Munoz, a spokeswoman for Petroleos Mexicanos, or Pemex, the state-run oil company.Munoz said preliminary reports indicate the explosion was caused by a leak in a gas pipeline.