An RCMP cruiser is seen in this file photo.

The serious injury of two men who were in a vehicle police were after has prompted Alberta's police watchdog to step in.

Police believe the vehicle was driven off an embankment.

It was found "heavily damaged" near Chipman around 8:30 a.m.

One of the men was flown by STARS, and the other driven by ambulance, to an Edmonton hospital.

Three hours earlier, mail was stolen from a post office in Veteran, 250 kilometres south.

RCMP from several detachments were dispatched to contain an SUV believed to be involved in the theft, and that's what they were coordinating when the vehicle was found, police said.  

The Alberta Serious Incident Response Team was directed to investigate.