First responders continued searching late Sunday night in the ocean off Smith Point County Park in Shirley for a swimmer who went missing earlier, officials said.

The U.S. Coast Guard received a call from the Suffolk County Police Department at about 6:40 p.m. reporting a man wearing a white and grey swim suit who never surfaced, the agency said in a news release.

The man is believed to be between 19 and 21 years old, Petty Officer Frank Iannazzo-Simmons said.

“The missing swimmer’s friends initially notified local life guards and park police that their friend swam out off the beach and didn’t return,” the Coast Guard’s release said.

The Coast Guard plans to send in new crew for the search around 2 a.m. Monday and a helicopter is scheduled to sweep the area at first light, Iannazzo-Simmons said.

Suffolk County Park Ranger Sgt. Bill Curcie said the man was among a group of six at the beach, three or four of whom were in the water before they got separated. One of the missing swimmer’s friends was rescued from the water by a park ranger, he said.

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“We had some kids in the water. I guess they went out a little deeper than they thought they could. They got separated,” Curcie said. “There were people yelling when they came out of the water. They started screaming, ‘My friend’s in the water.’ ”

Searchers in more than nine boats and a helicopter continued to search the waters until about 8:30 p.m.

Two rescue boats continued the search at 9:30 p.m.

The park’s lifeguards went off-duty at 5:30 p.m., according to Robert Kolar, chief of lifeguards.

Before the lifeguards left for the day, they posted signs warning of strong rip currents, which Kolar said were moderate to high Sunday.

Curcie said the water was “a little rougher than average” on Sunday.

The National Weather Service reported a high risk for rip currents off South Shore ocean beaches until 9 p.m. Sunday.

“That 70’s Band” had been performing at the Beach Hut in the park from 6:30 p.m. until shortly after 7 p.m., when they were asked to stop out of respect for the missing swimmer, according to saxophonist Steve Interrante.

The band asked beachgoers “to send out their love and prayers for the family,” Interrante said. “We’re all shook up over this.”

With Stefanie Dazio