Update, 10:35 a.m.: As of 10 a.m., firefighters were still on scene looking for "hot spots" in the roof of 17 Banks St.
Deputy Chief Patrick Sullivan said firefighters were called to the fire at 5:05 a.m. He said the fire was not suspicious, although a fire investigator was on scene Tuesday morning to investigate the blaze.
Sullivan said it was likely eight people were displaced by the fire: five at 19 Banks St. and three at 17 Banks St.
The Boston Globe reported that three cars in the driveway between the two homes also caught on fire
Two homes near Porter Square caught fire early Tuesday morning and one resident was sent to the hospital to be treated for smoke inhalation, according to Deputy Chief Patrick Sullivan of the Somerville Fire Department.
As of 9 a.m. Tuesday, a fire investigator was on scene to investigate the cause, and Sullivan said assessing the damage was "still a work in progress."
The three-alarm fire started at 19 Banks St., the deputy chief said, and the flames went out a window and spread to 17 Banks St., next door. There were "basically two house fires," he said.
According to Breaking News Network, a service that monitors first responder scanner transmissions, firefighters were on scene by 5:15 a.m.
Sullivan said residents—at least five—were "definitely displaced," but as of 9 a.m. Tuesday he didn't have the complete numbers.
The American Red Cross of Eastern Massachusetts responded to the fire to provide aid, according to an email from the Red Cross. The organization said it was told two families were affected.