DORCHESTER, MA — Alfredo Castro, a laborer for Hospital Laundry in Dorchester, was killed last night when a conveyor belt carrying clothes into a dryer he was repairing knocked him into the unit and slammed the lid shut, police said.

Unable to free himself, Castro, 31, died after spending six minutes in the dryer, which was operating at 120 degrees. Police said another employee heard a thumping in the dryer but did not suspect the source of the noise.

An employee heard a thumping in the dryer but did not suspect the source of the noise.

"When he went to investigate, clothing was being ejected on the conyeyor belt," said Lt. John Sullivan of Area C. Castro's body was found among the clothing.

Castro, who lived on St. Cyprian's Place in Roxbury, was pronounced dead at Boston City Hospital shortly before 8 p.m., Sullivan said.

Castro was believed to be repairing a timing mechanism in the dryer in the building, which is on Hoyt Street, when he was pushed in.