SALISBURY, Mass. — Divers have suspended their search of the waters off of Salisbury Reservation and the mouth of the Merrimack River for a missing boater who may have been captaining a boat that capsized off the north jetty at the mouth of the Merrimack River last night.

Coast Guard and Salisbury rescue boats have not called off the search for the missing man, one of four New Hampshire men traveling in the 36-foot recreational boat that ran into the jetty as the vessel entered the mouth of the Merrimack River around 10 last night. Pieces of the boat have been located, and some have been recovered.

A 36-year-old Kensington, N.H., man remained missing this afternoon. As of noon, name was not being released because the man's family had not been notified. The Coast Guard is still calling the effort a search and rescue, not a recovery.

Divers are expected to return to the water tomorrow at low tide around 1 p.m.

According to officials at the scene, the boat was traveling in a thick fog last night just inside the north jetty at the mouth of the river, an area known for swirling currents that can cause dangerous swells, particularly during shifting tides. High tide last night was at 9:24 p.m.

According to an official at the scene, the boat had a GPS system and the boaters may have been using it to navigate the channel, but the fog may have been too thick for them to spot the rocks.

A swell likely carried the boat onto the jetty, throwing two of the passengers from the boat. A third jumped from the boat and was rescued.

The Boston Coast Guard station received a 10 p.m. 'mayday' call from the vessel, a pleasure boat that home-ports in Hampton Harbor, and launched two 47-foot life boats and a 25-foot rescue boat from Station Merrimack River, as well as a Jayhawk rescue helicopter from Air Station Cape Cod. The helicopter was used to rescue one of the men who remained in the boat and subsequently jumped in. The fourth man was last seen on the sinking vessel.

Salisbury fire rescue boats also assisted in the search. Divers were on the scene this morning, and will return at around 2 p.m. when the tide shifts, making for clearer water.

The four boaters abandoned or were washed off their vessel and swam toward the nearby jetty.

Rescued last night by the Coast Guard were: Russell Hilliard, 50, of 212 Drinkwater Road, Hampton Falls, N.H., who was pulled off the jetty; Jacob Clark, 30, of 7 Landing Road, Hampton, N.H., who was pulled out of the river; and Mark Baillargeon, 51, of 11 Chapel St., Newmarket, N.H., who remains hospitalized with a back injury. He was airlifted to Anna Jaques Hospital in Newburyport, according to Steve O'Connell, spokesman for Essex County District Attorney Jonathan Blodgett.

The DA's office is investigating because a person is missing, O'Connell said. A Salisbury police spokesman said during a morning press conference that the accident was being treated as a crime scene.

O'Connell declined to speculate on whether alcohol or drugs were involved.

"It is still early in the investigation," he said. "All the facts and circumstances are under investigation."

He said the Environmental Police were doing an accident reconstruction and would be recovering the vessel, which is partially submerged somewhere near the mouth of the river.

Coast Guard Petty Officer James Rhodes said this morning that a helicopter resumed the search for the missing boater about 9 a.m. today, along with Coast Guard vessels from the Newburyport station.

The station reported that the men were not fishing, but were out for a night cruise. It's unclear if the men were wearing lifejackets.