Five people are dead from exposure to ammonia after an accident involving a tanker truck Friday night in Guerrero.

The five were traveling aboard a bus on the Siglo XXI highway when it was trapped in a toxic cloud of ammonia released when the tanker, a double tractor-trailer, rolled over and blocked the highway in La Unión.

Twenty-one other passengers aboard the bus were hospitalized for ammonia poisoning, as were several rescue workers, and residents of the area were evacuated from their homes.

Emergency crews worked through the night to clean up the ammonia spill. The accident was blamed on a mechanical failure.

Source: El Sol de México (sp)