Therrien said the damage might not have been so great if he had more firefighters to respond to the blazes.
"That was a million-dollar weekend for the city," Therrien said Monday morning. "Both nights we didn't have enough people, let's put it that way, because of budget (constraints)."
The latest fire erupted just before 10 p.m. Sunday after a man in a second-floor apartment at 112-114 Nichols St. apparently fell asleep with his cigarette still burning.
Jennifer Mieth, the state fire marshal's spokeswoman, confirmed Monday that the fire was likely caused by the man's cigarette.
The fire spread up to the third floor of the six-unit building and across to an adjacent apartment building at 134 Nichols St.
Seventeen people were displaced by the Sunday night fire, adding to the 22 people, 12 of whom were children, displaced by the Saturday night fire on Grant Street, said Deanie Harris, executive director of the North Central Massachusetts chapter of the Red Cross in Leominster.
The fire on Nichols Street prompted the evacuation of between 50 to 100 elderly residents to City Hall from a nearby high-rise on Connors Street late Sunday night, Harris said.
Mieth said the cause of the Grant Street fire has not yet been determined, but the fires were unrelated.
"Both of them, we're looking at to be accidental fires," Therrien said.
A fire official said Sunday that investigators were looking at the exterior of the Grant Street building for the source of the Saturday night fire.
Both fires started on the second floor and spread to an adjacent building.
Investigators are still interviewing displaced tenants to learn more about the fire on Grant Street, Mieth said.
"Until they talk to everybody, they can rule nothing in and nothing out," she said.
Therrien said there were only five firefighters on duty at the station on Saturday and Sunday nights.
"When one of those people is the dispatcher, that leaves four to respond," Therrien said. "Naturally, we don't like that situation."
The Nichols Street fire was around the corner from the fire station and the Grant Street fire was just southeast of downtown.
But Therrien said his department lost 12 people or roughly 25 percent of the force through cuts about two years ago, leaving only 33 full-time firefighters and no activated volunteers.
"Fitchburg lost people. Naturally, we lost people. Athol lost people. Everybody lost people," he said. "Right now we have call (volunteer) people, but they're deactivated because we don't have the money to pay them."
The city was also forced to shut down a fire substation in South Gardner, making response times to that part of the city much longer, Therrien said.
"I guess I'd have to say -- if you're looking for a culprit here -- as far as the budget cuts, you'd have to look to Boston," he said. "I think we've hit rock bottom, and I think we're at the point we're going to see the end of the tunnel."
Greg Snyder, a first-floor resident of the three-story building at 112 Nichols St., said he smelled smoke Sunday night and went to the upstairs apartment where the fire originated.
His friend Steven Voyer, whose 16-month-old son lives in one of the apartments, said he credits Snyder for getting many of the building's sleeping tenants out alive.
"He was the only one awake, and he woke everybody up -- kicked in a door," Voyer said. "He got them out. Another 15 minutes, there probably would've been casualties."
Snyder said police helped get out a man who was apparently sleeping in his apartment on the right side of the second floor, where the fire started.
"Everybody was pretty much asleep," he said. "I started knocking on everybody's door, getting people out."
Everyone got out alive and without any serious injury from both fires.
Some residents in the buildings hit by fire lost close to everything, while others were able to retain some or all of their belongings. It all depended on how much smoke, fire and water reached their home.
"We got a couple things out of the second floor," Voyer said.
On Monday, Betsy Harding and her family moved their belongings out of the first-floor apartment on Nichols Street where she's lived for 13 years.
Clothes and furniture were stacked up with old photographs and a large dollhouse -- all items that survived the smoke damage and the water which flooded the building.
"It was coming out of here like the Colorado (River) last night," Harding said.
Harding said Russ Croteau, the building's manager, was helping her find another place to live while she stayed at her daughter's home.
Harris said the local branch of the Red Cross was strained by fires on two nights in a row. It cost about $7,000 just to provide food, shelter, clothing, and counseling in the immediate aftermath, she said.
"These units were all destroyed -- fully destroyed. They've lost everything, from their photographs to their clothes to their toothbrushes," Harris said.
"It was actually pretty mild (weather) last night," she added Monday. "But people didn't have coats. Some of them were in their slippers."
