Seven Northwest Central Dispatch System employees in Arlington Heights were taken to a hospital  after a non-toxic gas was sprayed into the room where they were working, authorities said.

An electrical malfunction set off the fire suppression system that released the gas at about 3:30 p.m. in the dispatch headquarters at 1975 E. Davis St. in Arlington Heights, said Arlington Heights Fire Battalion Chief Bill Essling. Renovations are underway in the building, and work on Saturday apparently caused a spark but not a fire, he said.

“When contractors reconnected something, it created a spark and a short and subsequently set off the fire extinguishment system in the computer room,” Essling said.

The system sprays a nontoxic gas that won’t harm computer equipment, and it usually gives a warning before the gas is dispersed because it creates a white fog that is an irritant when inhaled, Essling said.

Because of the electrical short, there was no warning, and employees didn’t get the chance to leave the room.

No one was seriously injured or admitted to the hospital, although dispatch employees were evaluated as a precaution, Essling said. The facility’s computer equipment was not damaged.

The Northwest Central Dispatch System, which handles 9-1-1 calls for northwest suburban public safety agencies including Arlington Heights, Buffalo Grove, Elk Grove Village, Hoffman Estates, Inverness police, Mount Prospect, Palatine, the Palatine Rural Fire Protection District, Prospect Heights police, Rolling Meadows, Schaumburg and Streamwood, switched to its backup operations plan when the electrical short occurred.

While Arlington Heights firefighters were responding to the scene at the main dispatch center, Essling said calls were handled by personnel at a sister station in Schaumburg.

About two hours after the fire suppression system unexpectedly deployed, Essling said the dispatch center in Arlington Heights had called in off-duty employees and was back to handling emergency calls.

“No 9-1-1 calls were missed or dropped, and no dispatches were delayed,” Essling said. “Everything worked the way it was supposed to.”