RUMFORD – More than an estimated 100,000 gallons of water rapidly began filling the basement of the Tri-County Mental Health building on Saturday night after a sprinkler system pipe ruptured, Rumford firefighters said.

The flood submerged the oil furnace and possibly the elevator’s electrical system, Deputy Chief Richard Coulombe said on scene at 9:15 p.m. He was still waiting for firefighters inside to return and tell him the extent of the damage.

At about 7:15 p.m., a 4- to 6-inch pipe broke apart, filling the 100-foot-square basement with about 4 feet of water before a Rumford Water District employee could turn the water off from a control under Exchange Street, Coulombe said.

The flooding set off loud alarms that reverberated through downtown Rumford as firefighters quickly scrambled to set up hoses with which to begin draining the water. Two firefighters carried in a large gas-powered pump, which meant those entering the building had to quickly don breathing gear. An exhaust fan was set up just inside the Exchange Street doors to draw out gas fumes.

By 8:25 p.m., firefighters in the basement found the broken pipe and shut off a water valve to the sprinkler system, enabling the water district to turn the water back on.

A Central Maine Power crew shut down power to the building, due to submerged electrical equipment, and were still standing by at 9:15 p.m. waiting for Coulombe’s OK to restore power.

Meanwhile, the water was being drained into a catch basin at the end of Exchange Street, which empties into the Androscoggin River, firefighters said.

Initially, Coulombe and a small group of firefighters responded, then the deputy chief immediately sought more manpower on realizing the seriousness of the situation.

He expected the crew of about 14 to remain on scene for at least two hours or more, continuing to empty the basement.