The incident occurred in Middlesex County in Old Saybrook on Long Island Sound around 9:15 p.m., Monday, Sept. 2.
According to Will Healey, spokesman for the state Department of Energy and Environmental Protection Police, multiple agencies responded and found a single motorboat floating, half-submerged, near the Harbor One Marina in Old Saybrook.
A total of nine people were on the boat. An adult male was recovered dead, and six people were transported to the hospital, Healey said.
"There was significant damage to the boat, which hit the east-facing jetty at the mouth of the Connecticut River," said Healey.
The person found dead has been identified as Middlesex County resident Christopher Hallahan, age 34, of Westbrook, Healey said.
The group was returning from a day on Block Island when the crash occurred, DEEP. officials said.
Officials did not say if the boaters were wearing life vests.
The search for two missing adult males resumed at 8 a.m., Wednesday, Sept. 4.
This remains a developing story. Check back to Daily Voice for updates.
Click here to follow Daily Voice Washington-Roxbury and receive free news updates.