PORTSMOUTH — A "significant" gas leak from a 6-inch line, caused by a construction accident, led to evacuations of multiple buildings in the area of Hanover Street and Maplewood Avenue for about half hour Thursday morning, said Deputy Fire Chief James Heinz.

The gas leak was reported at 9:06 a.m. and the amount of gas leaked was so heavy, it triggered alarms in multiple area buildings, according to Heinz. Other alarms were activated when people in downtown buildings smelled gas and pulled alarms while self evacuating, he said.

Heinz said "a significant amount of product leaked" and that "even in small amounts, natural gas can be explosive." Police responded to the scene and assisted with cordoning off the area and keeping people away, Heinz said.

Fire Lt. Brian Ryll was in command of the scene and, said Heinz, reported that firefighters helped evacuate residents at Portwalk Apartments, at 99 Hanover St. and from several other area buildings. Firefighters observed a "construction-related hole" in the gas line, Unitil was called to respond and the Fire Department tested all of the involved buildings with meters, Heinz said.

Unitil reported it shut off gas to the line by 9:30 a.m. and Heinz said the scene was declared safe by firefighters at 9:34 a.m. Heinz said there were no injuries and the fast resolution of the potentially-dangerous situation was due to collaboration among firefighters, police and the gas company.