Emergency crews didn't know what they were getting into when they were called to a fire at a St. Boniface auto-repair shop Thursday morning.

After crews put out the blaze, an explosive device was found inside by investigators, and the bomb unit had to be called.

CTV News has learned a suspect broke into Eastside Collision & Mechanical Repairs Ltd. on Marion Street and started a fire.

Crews were called to the business on Marion Street around 5 a.m. Thursday.

Firefighters managed to get the blaze under control.

A few hours later, however, arson-unit members investigating the fire found what's believed to be a pipe bomb inside the building.

"There was a period of time when we were unaware of it and certainly very concerning to the officers involved and anyone who might be in the immediate area," said Const. Jason Michalyshen from Winnipeg police.

Employees had returned to the building after the fire was put out, but the facility had to be evacuated once more and nearby streets blocked off.

"It's very scary to think we could be in danger if something did blow," said Chris Kalata, who works across the street from the building.

Members of the bomb unit responded and safely diffused it.

Sources said a potential suspect in the case is a disgruntled customer, with a man having been removed from the property a few days ago.

Police wouldn't comment on either potential suspects, or a motive, on Thursday.

"We are thankful there were no injuries but this investigation is far from over," said Michalyshen.

If a suspect is caught, they could be facing charges for arson, break and enter and even disregard for human life.

Staff and the business said they were shaken by the incident. They spent the day giving interviews to police. The business is expected to re-open Mar. 2.

- with a report from CTV's Stacey Ashley