Four workers were killed and two others are in hospital today after one of the world's largest cranes collapsed at a U.S. oil refinery.

Five other workers were also hurt when the 300ft crane - capable of lifting a massive 500 tons - toppled in Houston, Texas.


The crane fell on top of a smaller crane and a workers' rest tent, but officials at the 700-acre refinery are still unsure whether the casualties had been on the larger crane or underneath it when it collapsed.