A 17-year-old boy drowned Sunday afternoon at Hampton Beach, New Hampshire, after a strong current swept him out to sea, authorities said.

The teenager was swimming with his family when, around 6:45 p.m., he was swept away by the waves. His father went into the water to try to rescue him, but also found himself in trouble, ABC News reported.

According to the New Hampshire State Police, lifeguards had finished their shift at 5:30 p.m. However, after receiving the alert at 6:44 p.m., they returned to the beach and the first rescuer entered the water at 6:48 p.m.

Both father and son were pulled from the water and CPR was attempted on the boy, who was taken to a hospital where he was pronounced dead. The father is hospitalized in stable condition.

Dangerous Surf from Hurricane Erin

Hampton Fire Chief Michael McMahon said the cause of the accident was not a rip current, but rather the strong surf conditions generated by Hurricane Erin.

A high surf advisory was in effect Sunday, with waves between 4 and 7 feet, and the beach maintained a red flag, restricting swimmers to wading in shallow water only.

Authorities reminded residents of the importance of swimming only when lifeguards are on duty and being aware of ocean hazards.

“It was low tide at the time,” McMahon said. “It’s a relatively calm period, but it doesn’t take much for someone to get into trouble.”