BAR HARBOR — A restaurant building badly damaged last week by a fire of unknown origin was demolished Monday.

Investigators with the state fire marshal’s office have said they were unable to determine what caused the fire, which broke out at the Portside Grill on Cottage Street at around 6 p.m. Sept. 2. The owner of the restaurant, Vicki Hall, said last week she was not sure whether she would rebuild. She could not be reached for comment Monday.

The fire started in the ceiling above the restaurant kitchen, directly below several second-floor apartments, according to the fire marshal’s office. The roof of the building partially collapsed, but firefighters from several area communities were able to contain the flames to the Portside Grill and save the surrounding buildings in the densely developed neighborhood.

An abutting business owner was still working Monday to have damage repaired so he could reopen. Basil Eleftheriou, who co-owns the Thirsty Whale Tavern with his wife, Heather Sorokin, said they continue to have some equipment and electrical issues because of the heavy amounts of water firefighters sprayed onto the roof of the tavern.

Their insurance company has been working with them to clean up their business, replace lost inventory and fix malfunctioning equipment, Eleftheriou said. Their goal, he added, is to re-open Wednesday, Sept. 10.

The Rite Aid pharmacy building, which abuts the Portside Grill on the opposite side, suffered minimal damage. The pharmacy business was open for business as usual the day after the fire. All buildings affected by the blaze were insured.

Despite lingering effects from the blaze, the tavern keepers and other nearby property owners have praised local firefighters for saving their structures.

About 18 Portside Grill employees lost their jobs because of the fire, but all have been offered seasonal work at other local businesses, Hall said last week. Hall and four of her employees who lived above the restaurant have been provided free lodging at the Wonder View Inn while they look for long-term living arrangements.

The American Red Cross of Maine has provided assistance for those displaced by the fire, and an online fundraising effort for employees of the Portside Grill and Thirsty Whale has raised more than $6,200.