The incident happened at the Maple Pointe Assisted Living Facility on Maple Avenue in Rockville Centre around 6 a.m.
A fire sprinkler line burst, flooding parts of the six-story building.
Workers inspected the flat roof for possible leaks due to snow and ice as authorities started to move approximately 136 elderly residents to the village recreation center in buses. Family members were also told they could pick their relatives up.
Workers were looking into whether the cold caused the fire sprinkler line to burst.
Ambulances and other equipment were stationed outside the building as authorities inspected the roof to determine the cause of the leak.