Firefighters work to extinguish a fire in a vacant home on Airport Road in Concord early Saturday morning. Credit: Jay Heath / For the Monitor

A long-vacant house on Airport Road sustained major damage in a fire early Saturday morning.

Concord Fire responded to the area, near the intersection with Manchester Street, just after 3 a.m. and arrived to significant flames on the second floor, according to Chief John Chisholm. Flames spreading into the attic and a discovery that the floor was not structurally sound prolonged firefighters’ work, and the blaze was contained around 4:42 a.m.

The cause of the fire hasn’t been determined, but it does not appear suspicious, officials said. While there was no electricity in the house, Chisholm said, there was evidence of people staying in the structure unsanctioned at one point.

The house is next door to, and owned by representatives of, the Concord Nissan dealership, according to property records.

Catherine McLaughlin is a reporter covering the city of Concord for the Concord Monitor. She can be reached at cmclaughlin@cmonitor.com. You can subscribe to her newsletter, the City Beat, at concordmonitor.com.