A fiery highway crash involving a passenger van and a freight truck killed 26 people in northern Mexico on Sunday, authorities said.

Prosecutors and police in the northern border state of Tamaulipas said the death toll was a preliminary count, apparently because of the sheer volume of the wreckage and the fire that consumed the van and the freight trailer.

The cab that had been pulling the freight trailer was not found at the scene, suggesting the driver might have uncoupled it and fled.

The accident occurred on a highway near the state capital, Ciudad Victoria, and the cause was under investigation, officials said.

Local media reported many of the victims might be members of an extended family returning from an outing, but authorities did not confirm that.

In the past, big death tolls in similar crashes in Mexico have often been blamed on overloaded vehicles linked to migrant smuggling.