At 7.33am on Tuesday (26) crews were called to a road traffic collision on the A47 near Guyhirn.
Two crews from Dogsthorpe, one crew from Stanground and one crew from Ely attended the incident.
Firefighters arrived to find a collision involving a bus and a heavy goods vehicle. They worked closely with ambulance crews to release a number of casualties from the vehicles.
Two casualties sadly died at the scene.
The crews returned to their stations by 10.40am.
The A47 will remain closed while recovery takes place and investigation work is carried out.