Some people in downtown Winnipeg were startled by an explosion inside a building on Portage Avenue and Smith Street this afternoon.

Emergency crews were called to the Sterling Building at 283 Portage Ave. shortly after 3 p.m. Wednesday.

Portage Avenue blast cleanup

Broken glass is cleaned up outside the building on Wednesday afternoon. (Tyson Koschik/CBC)

A section of the sidewalk outside the building was taped off as broken glass and debris were cleaned up.

According to police, it appears that a piece of equipment inside the building exploded somehow, shattering some windows in an upper floor as a result.

Edgar Rascon, who owns La Bamba Restaurant next door, told CBC News the blast shocked many people inside the eatery and on the patio.

"We heard this big, like, bang," he said. "My first thought was, 'Oh, a car must have, you know, hit the building or something along that nature.'"

Rascon said he ran towards the site of the blast to see if everyone was OK.

"As I was going up there, I was calling 911 and they were telling us, 'Oh, be careful, don't go up there,'" Rascon said.

"When we got to the second floor … the whole lobby on the second floor was full of steam."

Police said one person has minor injuries, but they don't know if that person was inside or outside the building at the time of the blast.