Earlier this week, a passer-by first noticed a fallen wall at the Empire Hotel on Simpson Street in Thunder Bay. The city will demolish the building this weekend. (Matt Prokopchuk/CBC)

The parts of the Empire Hotel in Thunder Bay that remain standing will come crashing down in a matter of days. 

After part of the back wall collapsed Tuesday night, Thunder Bay's chief building official said demolishing the entire structure is the prudent thing to do.

"The south wing [has] collapsed, and part of the centre section at the rear," Des Stolz said.

"We've determined the building is unsafe.  And it looks like more collapse is probably imminent."

Stolz said demolition should happen sometime this weekend.

The former Simpson Street hotel is owned by a numbered company from out of town.

Under an emergency order, the city can tear it down and bill the owners, Stolz said.

Part of the rear wall crashed to the ground Tuesday evening.

Stolz said he's never seen an incident like this in the city.

"It was surprising to me to see that happen ... without any indication [or] early indication."

The city does not routinely examine old buildings, he noted, but it will do a check when there's a complaint, or if an inspector has come across something that causes concern.