CHELMSFORD — A fire that started shortly after 11 p.m. Saturday in a fourth-floor condominium on Littleton Road tore through the unit and left a disabled man and a woman dead and four others injured, including a 7-year-old boy, according to fire officials.
The man and woman were at least in their 60s, according to State Fire Marshal Stephen D. Coan.
The 7-year-old boy was taken by MedFlight to a Boston hospital for treatment for burns, and the other three injured parties were taken to local hospitals, he said. Coan said the fire did not appear to be suspicious, but investigators have not determined the cause.
Two other lives were lost in weekend fires, including a 15-year-old girl in Holyoke on Saturday and a 70-year-old man in Winchendon, authorities said.
“It’s a very tragic weekend for us,’’ said Coan.
Authorities have not identified any of the victims and the conditions of the injured survivors was not clear.
Coan said the building at 181 Littleton Road in Chelmsford had working sprinklers only in the garage.
“Most likely, if that building had an operating sprinkler system, the outcome could have been different,’’ Coan said.
Plumes of black smoke poured out of the 21-unit building early this morning as firefighters continued to battle the blaze and shocked neighbors stood nearby. Crews were still dousing the smoldering wreckage early this afternoon.
“I’ve never seen anything like this, this up close,’’ said Maria Francione, 57.
Another neighbor, Mike Adams, 29, said he was driving home around the time the fire started and could see it raging from the road.
“It was a red horizon on the highway,’’ he said.
Coan said he did not know how many people were displaced by the blaze. The American Red Cross of Eastern Massachusetts said volunteers had provided 10 people from four units with emergency funds for food and clothing.
Paul Harrison, the property manager, said the building was equipped with working smoke detectors. He said the man who was killed used a wheelchair, as well as a prosthetic leg at times.
Janet Chapet, a board member of the condo developments in the area, said the deceased were a married couple whom she knew from board meetings. She said they were quiet and described them as a “very nice couple.’’
“It’s just awful,’’ she said of the blaze.
In Holyoke, a 15-year-old girl died in a fire that started early Saturday morning in a two-story, single-family home at 28 Glen St., according to fire officials. Firefighters found her in a room on the second floor.
“I believe it was a bedroom,’’ said Holyoke Fire Lieutenant Thomas Paquin. “It was all burnt out, so it’s hard to say.’’
He said the fire was accidental and probably started near a wood stove on the first floor.
“Investigators can’t get into the house, that section of the house, close enough to determine the cause exactly right now,’’ Paquin said, adding that the bungalow-style house is a total loss and will have to be razed.
Firefighters rescued one woman from the blaze, he said, and one firefighter suffered a knee injury. They also recovered a dog from the home, but two other dogs were unaccounted for.
Coan confirmed that the deceased was a 15-year-old girl, but he did not identify her.
On Friday evening, Donald Willett, 70, was killed in a two-alarm blaze at 95 Beachview Drive in Winchendon, according to fire officials.
Investigators have not released the cause of the blaze, but have said it appears to be accidental.
“Search crews were forced out of the building due to intense heat conditions and live power lines dancing in the area of the building entrance,’’ the Winchendon Fire Department said in a statement. “Further attempts to enter the building were thwarted by the heavy fire conditions and the imminent building collapse.’’