At least 14 people died and 19 others were injured Thursday when a bus collided with a freight truck in the northwestern Mexican state of Sonora, authorities said.

The accident happened before dawn on the road connecting Ciudad Obregon with Guaymas, the state coordinator for emergency services, Carlos Jesus Arias, said.

"So far there are 14 people dead," the official said, adding that the injured were taken to two hospitals in Ciudad Obregon.

The bodies recovered at the scene "are completely burnt" and will be difficult to identify, Arias said.

The crash was apparently caused by an attempt by the driver of the bus, en route to the border metropolis of Tijuana, to pass a cantaloupe-laden truck on a bridge, he said.

Some of the 19 injured survivors are in critical condition, authorities said.