A first responder with 20 years of experience says Sunday's crash in Vaughan, Ont., that killed three children and their grandfather has left his colleagues heartbroken.

"It's one of the most horrific things I've seen," Vaughan Fire and Rescue Deputy Chief Andy Zvanitajs told CBC Radio's Metro Morning on Tuesday. "From the collision and the damage to the vehicles, it's one of the worst ones I've seen in 20-plus years of being a paramedic and a firefighter. These first responders, these firefighters, are heartbroken." 

More than 30 first responders attended to Sunday's crash, which involved an SUV slamming into a minivan carrying six family members. At one point, firefighters and paramedics were working to resuscitate four people at once.

The Neville-Lake family's van was T-boned at the intersection of Kirby Road and Kipling Avenue, north of Kleinburg.

Three siblings – Daniel 9, Harrison 5, and Milly 2 – were killed along with their 65-year-old grandfather, Gary Neville. The children's grandmother and great-grandmother are in stable condition in hospital.

'It was an extremely tragic scene'

Andy Zvanitajs

Andy Zvanitajs of Vaughan Fire and Rescue said Sunday's crash, which killed three children and their grandfather, is one of the worst accident scenes he has seen in 20 years of working as a paramedic and firefighter. (CBC)

Marco Muzzo, 29, of King Township, who was driving the SUV involved in the crash, faces 18 charges, including four counts of impaired driving causing death.

Zvanitajs said that in addition to the devastation such a crash causes for the families, it takes a toll on those with the job of helping victims at the scene.

"It was an extremely tragic scene," said Zvanitajs. "When you add a child element to a call and then you multiply it by three or four, that compounds the effect on your mental fitness."

Zvanitajs said management teams of paramedics and firefighters are learning more about how dealing with heart-wrenching crashes can leave first responders with the effects of post-traumatic stress disorder.

He said that after the crash, paramedics and firefighters came forward, offering to work for those who were shaken by what they saw on Sunday.

"I had people literally lining up to say 'I will come in and work if these people want to go home,'" he said.

Zvanitajs also said impaired driving continues to take a heavy toll on families, despite years of police and governments drumming home the message about how it can devastate families.

"People can make choices and take responsibility for their actions and that's where it starts," he said. "Before you go out, have a plan."