At least 18 Mexican oil workers have been killed after a drilling rig hit an oil platform in stormy weather, spilling gas and oil into the Gulf of Mexico. Seven workers are still missing.

Rescuers have pulled 61 oil workers to safety from storm-tossed waters but have yet to control the oil leak, according to Mexico’s oil monopoly Petroleos Mexicanos, or Pemex.

The company said 81 workers and five rescue personnel abandoned a subcontractor’s drilling rig known as the Usumacinta after it hit the Kab 101 light-production platform amid 25-foot waves and winds gusting to 80 mph.

One survivor, Eder Ortega Flores, 25, told the Televisa television network that workers abandoned the rig amid the 25-foot waves only after leaking gas rose to unbearable levels and the supply of air from emergency breathing devices ran out. Once in the water, the waves battered the workers’ orange-colored, covered life rafts.

“The life rafts didn’t hold up under the force of the waves,” he said. “They broke up, at least the one I was on, little by little, until the raft sank, and all my co-workers went into the sea.”

The mishap occurred about 20 miles offshore from the port of Dos Bocas in Tabasco state.