Three people were injured Saturday night when a set of stairs connected to a rear deck detached in Hopkinton.
The collapse was reported at 36 Trevor Lane at 6:14 p.m.
The injured people were taken to hospitals in Milford and Worcester, said Hopkinton Fire Chief Ken Clark. He said the injuries were not described to him as life-threatening but did not have any immediate details.
The deck itself had about four people on it when the stairs detached, he said. Those people were not injured. One person, a woman, was pulled down when she reached out to try to grab someone on the falling stairs, he said.
The cause is under investigation by the town's building department. A building official was at the scene on Saturday. Clark said the homes on Trevor Lane are about 3 years-old.
Assisting Hopkinton with the rescue were Southborough, which took a patient in its ALS ambulance to Milford Regional Medical Center, and Westborough, which took a patient to UMass Memorial Medical Center, a trauma center.