LEWISTON – An afternoon fire at a downtown business Thursday caused an estimated $1 million in damage and losses, investigators said Friday.

Officials said the blaze at Financial Institutions Services Corp. on Lisbon Street likely was caused when chemicals used to clean and service computer equipment mixed together and ignited.

Lewiston Fire Investigator Paul Ouellette and a city electrician spent part of Friday at the fire scene searching for the source of the blaze. After electrical causes were ruled out, the investigators found that some of the chemicals stored near computer equipment on the second floor made for a noxious mixture.

“There were six or seven different chemicals in there. Indications are that one chemical was reacting with another,” Ouellette said. “It’s a unique situation.”

It was not clear Friday exactly which chemicals caused the fire. Investigators were unable to enter the burned portion of FISC until Clean Harbors crews cleaned the fire scene and made sure it was safe.

Employees at the check processing office were able to continue working Thursday night due to saved software and a backup plan for emergencies.

FISC President Carol Sebasteanski said that although the company was set back a few hours by the blaze, the effect on customers was expected to be minimal.

“Some of the computer software was saved and some of it was lost,” Ouellette said. “But they had a backup plan. They were prepared.”

Ouellette said most of the damages were the result of property lost and burned company software. Workers at FISC worked from another downtown building until they were able to return to their offices at 168 Lisbon St. on Thursday night. By Friday morning, it was business as usual, except for the investigators picking through the rubble on the second floor.

No one was hurt in the fire. Fire officials said smoke alarms inside the building alerted occupants to the flames. Employees and tenants in adjacent apartments cleared the building as fire crews arrived.