LAWRENCE — A three-decker went up in flames Thursday, sending billowing smoke into surrounding homes and displacing six families.

At about 1 p.m., firefighters and police responded to several 911 calls of a fire at 267 Water Street. According to police Lieutenant Shawn Conway, an elderly woman was rescued from the second floor of the adjacent three-decker, which sustained damage from heat, smoke, and water.

Conway said the fire appears to have started on the second floor and quickly spread to the rest of the building, as well as damaging the house next door. Six families were evacuated from the two structures and are now without a place to live. One of the buildings is considered a total loss.

State Fire Marshal Stephen D. Coan said Thursday evening that investigators were still trying to determine the cause of the fire. All Lawrence fire units responded and mutual aid was requested for the three-alarm fire.

At the scene, Nori Luciano, shirtless and wearing one sock, watched firefighters put out the fire.

He said he heard the smoke alarms go off and quickly ran into his daughter’s room. There was smoke coming from under her bed, and then flames began rising on the wall.

“It took seconds, maybe 20 or 30. Then everything went into the air,” Luciano said.

Luciano said he ran to make sure everyone else was out of the building, banging on walls and yelling, “Get out, get out.”

“I’m just glad that everybody is safe,” he said.

Mayor William Lantigua arrived at the scene around 2:30 to examine the damage.

“I represent this community. This is our city, and I’m here to see what I can do,” Lantigua said.

Lantigua commended the quick response of fire officials, saying the damage could have been much worse.

“These homes are so close together,” Lantigua said. “This whole block could have been up in flames.”