At least 11 people died and 75 were injured in a pile-up on a highway in the western Venezuelan state of Zulia that included a truck and two buses, authorities said Thursday.

"We presume that the driver (of the truck) stopped because there was a thick cloud of smoke ... which impeded the visibility of the traffic, and the buses came from behind," Henry Uzcategui, the fire chief in Santa Rita, told reporters.

This is "only a hypothesis," he added.

The crash occurred shortly before midnight Wednesday.

The buses were heading for Caracas at the time of the pile-up, in which three other automobiles were involved.

The Nacional newspaper said the buses were carrying partisans of President Hugo Chavez to the capital for a rally to support the ailing head of state.

Alessandro Galattioto, the fire chief in the city of Cabimas, said that the injured had been taken to hospitals in his jurisdiction, which includes Maracaibo, Lagunillas and Simon Bolivar.

Most of them, Galattioto said, are in "serious" condition, according to the Maracaibo daily La Verdad. EFE