Firefighters responded early Saturday morning to a house fire in East Boston, where they found the top floors of two neighboring triple deckers engulfed in flames. The initial call around 1 a.m. was for 1051 Saratoga Street, but the blaze in the building’s rear spread quickly next-door to 1053 Saratoga Street, according to the Boston Fire Department. No residents were injured, but the fire has forced 34 people who lived the buildings’ six apartments to find alternate shelter.