Conservative MP Ryan Leef said there was “a lot of chaos” after two explosions rocked the Boston Marathon finish line Monday afternoon, killing at least two people and injuring dozens of others.

Leef had finished the race shortly after the three-hour mark and had made his way through the finishing shoot, where runners collect their belongings and pick up food and water.

Leef said he did not hear the explosions, but knew “something serious had gone on,” when he began seeing emergency personnel rushing toward the scene.

“Immediately from all directions the emergency personnel were racing there,” Leef told CTV News Channel in a telephone interview as he drove back to Ottawa.

“And of course your mind doesn’t turn itself to thinking, ‘Oh, there’s been an explosion.’ You just make a quick assumption that there’s been medical emergencies that aren’t uncommon in marathons.”

Authorities said late Monday afternoon that at least three people were killed and at least 130 were injured in the blasts. Authorities also revealed that another blast at the John F. Kennedy library may have been related.

Canada’s Foreign Affairs Department confirmed late Monday that no Canadians were injured in the blasts.

The blasts at the marathon finish line occurred at about the marathon’s four-hour mark, which Leef said “would have been the most volatile time in terms of congestion, for runners finishing and runners who had finished being around the area, and the volume of spectators.”

Kevin Donnelly, a marathoner from Winnipeg had completed the race just after the four-hour mark, saw and heard the first explosion.

“My first thought was that there was some sort of calamity of some nature, I saw the smoke and the explosion,” Donnelly told News Channel. “My first thought was to look up and to see if there was a building coming down. But when none of that happened… we all just sort of stopped in our tracks.”

Brian Leverton and his wife were among the approximately 2,078 Canadians registered for the marathon, but neither could run due to injury. They travelled to the city anyway to celebrate their anniversary, and take in the race as spectators.

Leverton, who hails from St. Thomas, Ont., said the explosions sounded like large trucks rumbling over train tracks.

“You don’t know what to do…you know what it is, but you don’t know where to go,” Leverton told News Channel in a telephone interview.

“You see all these kids crying and you feel bad for the kids … It’s a mass panic.”

Leverton said he, his wife and other spectators immediately began running from the area and sought refuge at a nearby hotel.

Shortly after word of the explosions broke, Prime Minister Stephen Harper issued a statement to say he was “shocked” to learn of the news from Boston.

“It is truly a sad day when an event as inspiring as the Boston Marathon is clouded by such senseless violence,” Harper said.

“Our thoughts and prayers are with those injured or affected by this horrible incident.  We stand with our American neighbours in this difficult time.”

Laura McLean of Toronto was being treated for dehydration in a medical tent when she was asked to make way for victims of the explosion.

McLean told The Canadian Press she saw victims who were “really, really bloody.”

Jordan Back of Vancouver finished the race in 2 hours, 41 minutes and had gone back to his hotel before the explosions. He had been back at his hotel, which is not far from the finish line, for about 40 minutes when he started hearing sirens and seeing emergency responders headed toward the scene.

He said Massachusetts National Guard members who had completed the marathon returned to the area to help close the course.

Back said after the scene was cleared, a “calmness” settled over the area.

“I would say the mood now is kind of an eerie calm,” Back told News Channel.

Mark Rosenberg of Vancouver said he had finished the race and had just walked through the area where runners collected food and water when he heard an explosion and saw smoke, and then heard a second explosion.

“Then we heard the ambulances and they cleared the street so the ambulances and the first responders could get through,” Rosenberg told News Channel.

Rosenberg said he began texting friends and family to let them know he was safe.

Scott Rintoul, a radio reporter from Vancouver, had also completed the marathon before the explosions hit. He said thousands of runners and spectators were still in the area when the blasts went off.

Rintoul told CTV British Columbia that the explosions went off on the north side of Boylston St., directly across from stands that were assembled for spectators to watch the race.

“There are also thousands of people who line the streets. There are patios, but literally there are thousands of people in that area,” Rintoul said.

“It is a stream for everyone who runs that marathon.”

If you're a Canadian involved in the Boston Marathon explosion and need assistance, contact @TravelGoC 1-800-387-3124 or sos@international.gc.ca.