The woman who tried to administer CPR to a dying motorcyclist in Sunday's fatal crash says it will take her some time to recover.

"I think it's the worst thing I've ever seen in my life and it's going to take, I think, a little bit of time to get over," Alexandra Mackwood told CBC News.

On Sunday afternoon a 49-year-old man and 34-year-old woman on a motorcycle died after a collision with three other vehicles on Montreal Road. Police said the incident happened near the Highway 174 off ramp just after 4:30 p.m.

Mackwood was driving eastbound when her boyfriend alerted her to the crash up ahead.

"I heard him say 'Oh God' and looked up and saw a helmet go flying," she said.

The 28-year-old quickly pulled over and she and her boyfriend took turns performing CPR on the male driver. She said the female passenger was unresponsive.

"There was nothing I could do for her," said Mackwood.

Police looking for witnesses

When Mackwood first arrived on the scene there was another motorcyclist trying to resuscitate the driver, but she could see he was struggling.

"I offered to take over for him and continued CPR until the first responder RCMP vehicle arrived," she said.

Mackwood said although she and her boyfriend could not save the two motorcycle victims, she's thankful she was able to use her life saving skills.

"If you have the opportunity to be CPR certified you should absolutely do it. I think that there were some really great people there that day that did the best they could."

Ottawa police are hoping to speak to anyone else who might have witnessed the collision to get a better understanding of how it happened.