KANDAHAR, Afghanistan — They were out testing some new equipment, just outside the security fence that surrounds the massive NATO military base in Kandahar.

They were so close that they didn't even have flak vests on -- their "kit," as soldiers call it.

That's when the trio of Canadian soldiers heard an explosive boom, said Sgt. Marc Andre Rousseau, one of the three who received a commendation Friday for their courage during the Aug. 3 insurgent attack on Kandahar Airfield, the largest NATO base in southern Afghanistan.

After taking cover in a bunker, they heard another rocket-propelled grenade explode about 50 metres away, and a firefight break out involving a group of U.S. soldiers who also happened to be in the area when the daylight attack occurred.

They quickly decided to act.

"I told them let's go, we're going to return fire," said Rousseau, a commander of the Combat Engineers in Kandahar and a member of the Royal 22e Regiment, based in Valcartier, Que.

"We ran outside the bunker. There, I looked to my right and we got a visual contact with the insurgents."

"So, we ran out from the bunker with no kit. 'Oh my God, they're right there'," recalled Rousseau, 27.

The attackers were about 75 metres away, firing on the Americans with AK-47s and a RPG.

Sapper Kirk Farrell, a 29-year-old soldier from Petawawa, Ont., jumped in the driver's seat of their light armoured vehicle, and Cpl. Joseph Henry, 32, also a member of the Combat Engineers from Valcartier, took command. Rousseau climbed into the gun turret mounted on top of the vehicle.

"At the moment I'm aiming at the insurgents, the first guy blew himself up. That makes a big dust cloud," he said.

Rousseau said he knew the suicide bomber was too far from the rest of the insurgents to have killed them in the explosion.

The other insurgents were obscured by the dust somewhere between the Canadians' vehicle and a hole in the fence from the suicide bomb.

Rousseau took aim at the dust cloud where he'd seen the attackers. He unleashed 10 rounds of 25mm incendiary ammunition, which explodes on contact.

When the dust lifted, between eight and 10 attackers were dead.

"It wasn't pretty," he said. "If you hit directly someone with that, they completely disappear, kind of. So it's hard to say exactly how many there were."

Royal Air Force Air Commodore Gordon Moulds, commander of Kandahar Airfield, presented the trio with certificates commending them for "courage, excellence and steadfastness in the face of danger."

The special ceremony was held in front of the memorial to Canadian soldiers who have been killed in action in Kandahar.

Rousseau, who is on his second tour in Afghanistan, is proud of the actions he, Farrell and Henry took, although he said he acknowledged it may be difficult for anyone outside the military to understand that pride.

"You train really hard to be ready for this experience. So when it happens to you, it's hard to understand for civilians ... when you're well-trained and you know what you're doing and if you're sure that what you do is right, you feel good."

It is not the first time he's been in a firefight with insurgents. Two fellow soldiers were killed by roadside bombs during an operation to take back a forward operating base at Ghundy Ghar from the Taliban in 2008.