"We heard a few shots at the beginning and everyone was looking at each other saying, ‘Maybe it’s only renovations' ... but after three or four shots, it was quite clear there was an attack," the MP for Rosemont-La Petite-Patrie told CBC Montreal's Homerun.
He said those in the room had gotten up to leave when security guards told them to stay where they were.
"Security guards came in and said, 'No, you cannot leave the place. It’s not safe. Go under the tables.' They were guarding the three doors and locking them. After that, we heard maybe two or three other shots, and after that it was silence."
Boulerice says MPs were unaware of what was happening, but it was clear something was wrong.
"It was quite frightening. I have to say, it was surreal. Like living in an action movie.
"Now we know the guy was alone here in centre block. But when you hear 20 to 25 shots, you think, 'How many are they? What's happening on the other side of the door? Are the guards winning this battle or not?' So many of us thought, ‘OK, this might be the last day of my life.’"
Boulerice said he hid under a table, holding on to his colleague Marjolaine Boutin-Sweet, MP for Hochelaga. Soon, the MPs were moved to a secure room.
Boulerice said he could smell gun powder.
"There was some running and people were in shock after that. Some cried, of course. I remember the first text message I was trying to write, it was very difficult because my fingers were shaking."
MPs who were in the building when the shooting started have been in lockdown since this morning.
Boulerice said they have access to cell phones and televisions and aware of what's going on.
He said the caucus's thoughts are with the families and friends of the victim, Cpl. Nathan Cirillo, a reservist from Hamilton.
"My thoughts are with the family of this military man who was killed today. It’s really too sad and tragic."
Irwin Cotler calls shooting 'unprecedented act'
Liberal MP Irwin Cotler, MP for Mount Royal, was walking to his caucus meeting when a security guard stopped him.
"[He] said to me, Mr. Cotler, you can’t go any further. I said, 'I have a caucus meeting starting.' He said, 'No, the building is now under lockdown and everybody is being evacuated so you better go back to your office and don’t leave.' And that’s exactly what I did."
He's also been locked down in his office, where he says he is trying to do work. But he says he's shaken by the attack on parliament.
"I think there is a sense of concern that this is an unprecedented act. I don’t recall in all my 15 years as a Member of Parliament any shootings within parliament.