BREWER (AP) – Maine officials have filed charges against the president of a New Hampshire company that installed a heating system linked to carbon monoxide poisonings at a 31-unit apartment complex in Brewer this month.

The Department of Professional and Financial Regulation issued a summons to Concord Gas Heating Service President James Kane for unlicensed practice. If convicted, Kane could face up to six months in jail and a fine of up to $10,000.

Agency spokesman Doug Dunbar said technicians who work for out-of-state companies are required to be licensed in Maine when working in the state. Brewer officials have said Concord Gas did not have a city permit to do the work.

The carbon monoxide leak is thought to have been caused by a vent pipe that separated from a furnace. Eight residents required hospital treatment.