Many Montrealers were wondering what on earth was going on last night when their windows started shaking and they heard a deafening noise coming from the sky.

A CF-18 fighter plane passing over the Alouettes game at Percival-Molson stadium worried a lot of people.

Painted to honour Canada's 150th birthday, it passed over Montreal at the relatively low altitude of about 150 metres.

After it passed, police say 911 received calls and social media lit up.

The Royal Canadian Air Force and the Alouettes tweeted about it, warning of the flyby, but many weren’t aware it was about it happen.

While there are hundreds of flybys at special events across Canada each year, the air force says it is careful to ensure public safety at all times.

Not everyone was impressed, however.

“It's quite a loud sound and it's kind of invasive and I wonder, the celebratory aspect is for a very small population and it affects the whole island,” said St-Henri resident Douglas Scholes.

Flight trainer Firas Khelifi said he understands some people could be put off by such an intense noise.

“I understand that some people have had a certain trauma and might associate that sound with bad memories, but I think if anything people should be curious about this technology,” he said.

Khelifi, who watches planes take off every day, said the flyby was the coolest thing he's ever seen 

“The sound, how loud it was, it was just a big adrenaline rush for me,” he said. “It was just truly something that I've never experienced before.”