Al Siciliano was on his back porch in East Boston Wednesday morning when he saw that a five-family house behind his had caught fire.
At first, the blaze didn’t seem like much, the 73-year-old Siciliano said, but the flames quickly spread, igniting a six-alarm fire that destroyed two residential buildings and damaged a third, causing $1.2 million in damage, officials say.
“The house was on fire. It wasn’t that much of a fire,’’ said Siciliano, who lives on Webster Street. “But it went up in a minute. The whole house went up. And they were yelling: ‘Get out! Get out, everybody!’ ”
The fire could be seen far beyond the city limits, as a plume of smoke from the alley where the buildings are located rose above the skyline. Two firefighters were injured but no residents were hurt, said Steve MacDonald, a Boston Fire Department spokesman.
Fire investigators believe an electrical shortage in a first-floor apartment at 309 Sumner St. caused the blaze, which then spread to an adjacent home at 102 Webster St., where Jeanette D’Angelo was inside with her three small dogs.
From his porch, Siciliano said he called 911 and saw a man banging on a door at 309 Sumner St. to alert residents.
“He was banging on the doors” and shouting for people to leave, he said. “I was yelling, too, ‘Get out! Get out!.’ ”
Siciliano and his wife, Karen, said they called out to D’Angelo, who has been their neighbor for 20 years.
“She didn’t know even know what I was talking about,” Karen Siciliano said. “We were all nerved up. This went up in like five minutes, the fire. If this was at night or a windy day, forget about it.”
After exiting her house, D’Angelo realized she had locked the front door behind her, leaving her dogs — Shawnee, Spanky, and Daphne — behind.
Neighbors came to her aid, including Greg Kruszewski, who went inside the home with her to fetch the dogs.
D’Angelo and Kruszewski found two dogs in a staircase and a third hiding underneath a table on an upper floor.
“I was really focused on getting Jeanette and the dogs out as quickly as possible,’’’ Kruszewski said.
While inside, Kruszewski said, he noticed that the temperature in the house was steadily and quickly rising. Still, Kruszewski joked, he was no hero.
“No bravery involved in this instance,’’ he said.
The initial report of the fire came in at 8:16 a.m. When firefighters arrived at the scene, they faced challenges attacking the blaze because the residence that caught fire, 309 Sumner St., was located behind other buildings on Sumner Street and accessible only by an alley.
“The main fire building is set back, and it’s surrounded by two [buildings],” said Boston Fire Commissioner Joseph E. Finn.
“It’s kind of planted in the middle, so it’s making it difficult to get to the building.”
This was the first major blaze firefighters have faced since Finn took the oath of office as commissioner and chief on Monday. He said that initially there were reports, which proved erroneous, of people trapped inside buildings.
“We had heavy fire on arrival in two buildings,’’ Finn said. “Thank God everyone has been accounted for.’’
He said East Boston’s cramped neighborhoods of wood-frame homes are troublesome for firefighting.
“This is one of the most difficult neighborhoods in the city to fight fire in,” he said. “Look at the proximity of these homes. Something gets going, it advances very rapidly.”
One firefighter was treated at a hospital for a leg injury and later released, MacDonald said. Another firefighter fell down stairs and was being evaluated at Massachusetts General Hospital for head, neck, and back injuries, he said.
Residents at a third building, at 319 Sumner St., were also displaced from their duplex due to water and fire damage, he said.
An estimated 160 firefighters battled the blaze. At one point, firefighters were ordered out of two of the buildings for safety because of the volume of fire, MacDonald said. Once the blaze was declared under control, firefighters reentered 102 Webster St. to extinguish the flames, he said.
The blaze displaced 21 residents, according to MacDonald. Six families are being assisted by the American Red Cross, the agency said.
Kruszewski reflected on how vulnerable his neighborhood is to fire.
“These houses are so old,” he said. “They’re like a bonfire waiting to be lit.”Evan Allen and John R. Ellement of the Globe staff contributed to this report. Laura Crimaldi can be reached at email@example.com. Follow her on Twitter @lauracrimaldi.