Emergency demolition crews were called out after fires Monday night and early Tuesday.
Authorities said the origin of at least one of the fires, an early morning blaze Tuesday on Welch Avenue, was considered suspicious.
The India Kitchen, formerly the Castle Court restaurant, and the attached office for the Castle Motor Inn at 9802 Niagara Falls Blvd. were demolished Tuesday afternoon after a fire destroyed the business Monday night.
Damage to the restaurant -- which had a bar, fireplace and banquet facilities -- was estimated at more than $100,000.
Vishal Patel, the 21-year-old owner of the motel, declined to comment on the fire but did say Tuesday that he plans to keep the motel open.
Patel told Niagara Falls police that he was in his office when restaurant manager Bhupinder Singh ran in and yelled that the motel was on fire.
Fire Chief William MacKay said the fire broke out just after 10 p.m. Monday in the kitchen.
"We believe the fire started in a void between the ceiling and the roof in the kitchen. We found numerous extension cords running through the plenum space," MacKay said.
Smoke spread to the motel in the rear of the property, and 26 of the 35 motel rooms occupied at the time were evacuated, MacKay said. Several people were treated by a Rural/Metro Medical Services ambulance crew for minor smoke inhalation, he said.
"There are two buildings [in the motel] which are connected by a breezeway. Fortunately, there are block walls between them, but there was a lot of smoke and water damage," MacKay said.
An emergency demolition of the restaurant and the connected motel office was ordered just after 2 p.m. Tuesday because of structural damage caused by the fire.
The motel will remain intact.
St. Johnsburg volunteer firefighters assisted Niagara Falls firefighters at the fire.
City firefighters also were called to a fire just before 4:30 a.m. Tuesday at 2237 Welch Ave., where they found the unoccupied wood-frame home engulfed in flames.
MacKay said the fire appeared to have started on the third floor of the three-story structure.
Firefighters were at the scene for two hours. The home also was ordered to be demolished.
MacKay said the cause of the fire remained under investigation Tuesday, but firefighters were "leaning toward suspicious" as the origin.