A 17-year-old was found dead Wednesday after he went missing during swimming drills in the Gulf of Mexico, officials said.

William Zhang was visiting Indian Shores, Florida from Quebec, Canada for a swim camp, according to a release from the Pinellas County Sheriff's Office. He was swimming with his teammates in the ocean before 9 a.m., but did not return to shore with the group, the release states.

PCSO, along with a number of local departments, conducted search efforts. Zhang was found by the Underwater Search and Recovery Team shortly after 5:20 p.m. and pronounced dead.

The coaches told police they had checked for riptides and hazard, the release states.

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Adult told witness, 'There's still one in the water'

Witness Rick Ross told FOX 13 Tampa Bay an adult who stayed on shore called in the group because she became concerned about them being too far out.

"They all came in. Then she ran up the hill and asked me for the address here. I said, ‘What for?’ She said, ‘There’s still one on the water,'" Ross told the local station.

Authorities arrived in minutes, and one even grabbed a surfboard to start paddling out, Ross said.

The U.S. Coast Guard was involved in the rescue, and spokesperson Nicole Groll told USA TODAY Thursday that the swimmers were approximately 200 yards out. While she did not know the water conditions the time or if a riptide was a factor in Zhang's death, she said it was stormy during Wednesday's search efforts.

PCSO said the incident does not seem suspicious in nature and the investigation is ongoing.