The two who died, 51-year-old Paddy Bailie from the Kircubbin area who was driving, and a 28-year-old man, were in the Ford Transit van which burst into flames after it was in collision with a Lexus car at 8.15am on Tuesday morning.
But the terrible toll would almost certainly have been even worse but for the courage of Watch Commander Stephen Brown, who is based at Whitla Fire Station. He was on his way to work when he was first on the scene at the collison which witnesses described as "horrific".
Mr Brown helped three people from the van which by that stage was engulfed by flames and, as he was wearing motorbike protective gear, then acted as a barrier between the heat of the fire and a badly injured man in the car.
Another off duty Firefighter, Paul Cassidy who is based in Cadogan Fire Station on the Lisburn Road, also arrived on the scene and was able to assist the Ambulance Service and the initial attending Fire Crews.
Station Commander Neil McGrath from the Fire and Rescue Service commended both men and said without their help the accident could have been even more tragic.
"A Fire Appliance from Carryduff Fire Station was quickly on the scene to extinguish the fire and Fire Appliances from Ballynahinch and Central Fire Stations were able to free the casualty trapped in the car using cutting equipment.
"Our sympathy is with the families and friends of the deceased."
He added: "NIFRS is proud of the quick and brave actions of Watch Commander Brown and Firefighter Cassidy and without Watch Commander Brown pulling three people from the burning van we could have been looking at an even more tragic incident. He may be trained to do this but he was off duty and not in his protective uniform and showed exceptional bravery helping those men. Without a doubt more lives would
have been lost without his help."
The family of second victim have asked for his details not to be made public.
It is believed both men were employees of local firm North Down Marquees.
Three other men remain in the Royal Victoria Hospital after the collision. One of the men was described as being in a critical condition. The other two are said to be in a stable condition.