OTIS -- Authorities have identified the 22-year-old Otis man who drowned in the town reservoir on Sunday.

Citing a state medical examiner's report, the Berkshire District Attorney's Office says Derrick J. Vonberg Jr. of Alterie Road died as the result of an accidental drowning.

The search for Vonberg began Sunday afternoon when police and fire departments responded to a 911 call that he had gone under water.

Vonberg's body was recovered shortly after 3 p.m. on Tuesday.

Authorities say Vonberg's father, 44-year-old Derrick J. Vonberg Sr., was unsuccessful in an attempt to save his son and was pulled from the water by a boater who rushed to the scene to help.

Otis Fire Chief Sandy Pinkham said the Vonbergs and a family friend were out on the water in a boat Sunday, at about 2 p.m. The father and son jumped in to cool off while the third man stayed aboard and discovered a problem with the motor.

As the third man attempted to fix the engine the wind had pushed the boat away from the two swimmers. With the distance between them growing the father and son struggled to swim back to the boat.

"The father said he did all he could" to save his son, according to Pinkham.

The father was able to make it back to the boat but the son had disappeared into the water near the north end of the reservoir, roughly three-quarters of a mile for the former J&D Marina.

Pinkham said divers from the state police, Pittsfield Fire Department and Berkshire Sheriff's Office helped in the search effort.