EASTON, Mass.—A Massachusetts woman who went missing last week has been found alive in a swampy area of a state park after hikers heard the woman’s cries for help, police said.

Emma Tetewsky, 31, was reported missing on June 26, and police in recent days had appealed to the public for help in finding her.

Officers were called Monday evening to Borderland State Park, about 30 miles south of Boston, after hikers called 911 and reported hearing a woman’s screams coming from a swampy area of the park, according to Easton Police investigators.

Police arrived and heard Ms. Tetewsky’s cries through thick bush, but couldn’t see her. Then, three officers waded about 50 feet through the swamp to reach Ms. Tetewsky, authorities said.

Investigators said the woman might have been trapped in the swampy area for at least three days.

Ms. Tetwesky was taken to a hospital with what investigators described as serious but not life-threatening injuries.