Vancouver police said the "improvised explosive device" found in a Mount Pleasant storage locker this week could have caused extensive damage to the building – and anyone inside.

Someone found the device in a locker at Guardian Storage on West 7th Avenue and Columbia Street early Tuesday afternoon and called 911, triggering a massive police response.

Police said they are not sharing "exactly what the explosive device was," for "investigative reasons." But Vancouver Police Staff Sgt. Randy Fincham said it was large enough that it could have done significant damage to the building itself or anyone inside, had it not been discovered.

"Our focus right now is to determine exactly how that explosive device ended up in that storage locker, who placed it there, and any other information we can find in regards to that storage locker," Fincham said.

The device brought dozens of police officers, an Emergency Response Team and explosive technicians to the scene, which is just a few blocks away from VPD headquarters. Officers closed off an entire city block as a precaution.

An employee of Kit and Ace, a clothing company on West 7th Avenue, said more than 200 employees were sent home early.

The evacuations left many who live and work in the area concerned.

"The decision to evacuate last night was for the safety of the occupants, anybody working in the area, as well as the safety of our officers," Fincham said Wednesday.

Once the area was clear, a remote-controlled robot was sent into the storage facility and several loud sounds were heard.

"That’s part of the rendering safe procedure. Carefully targeted water charges that will disable an explosive device. That’s likely what you would have heard last night."

Fincham said officers are still trying to determine who owns the storage unit and who placed the device inside.

"It wasn't something you would traditionally see on the streets of Vancouver," he said.

"We don’t know what (else) we’re going to find in that unit….based on what we found there last night so we will be very cautious when we do that."

With files from CTV Vancouver's Ben Miljure