A woman, who went missing during a swimming club session in California, may have been the victim of a shark attack.

On Sunday, Dec. 21, the 55-year-old swimmer, who hasn’t been named, was reported missing off Lovers Point in Pacific Grove, Monterey County, at around noon, San Francisco Chronicle, SFGATE and CBS News reported. Two witnesses told authorities that the individual may have come into contact with a shark.

The Pacific Grove Police Department confirmed the incident is being treated as a possible shark attack, per CBS News

A witness told police that they saw water splashing when the woman disappeared around 100 yards off Lovers Point, according to the outlet.

Pacific Grove California (stock image).adamkaz/Getty

“We had a swim club that does a weekly swim out here off Lovers Point,” Pacific Grove Police Department Commander Brian Anderson told CBS News. “They immediately called all the swimmers in and there was one swimmer who hasn’t reported back yet.”

The group came to shore after one person said they saw a “large splash,” per SFGATE. They then realized that a woman in their club was missing.

“The person who reported the shark sighting claimed they saw a shark breach the water with what appeared to be a human body in its mouth,” he said, per SFGATE. “They then witnessed the shark submerge below the waterline without resurfacing.”

Sappey added, “I can confirm that there was a reported sighting in the area, however we cannot necessarily correlate this sighting with the missing person as there is no confirming evidence of that.”

A search and rescue response has been launched by the Pacific Grove Police Department and Monterey Fire Department, according to the San Francisco Chronicle.

The U.S. Coast Guard, Monterey County Sheriff’s Office and California State Parks are also assisting in the operation, which includes boats, drones and a helicopter.

Lovers Point Beach and nearby beaches in Monterey are expected to remain closed through Tuesday. An advisory was in place for Alisomar State Beach, Monterey Municipal Beach, Del Monte Beach and Monterey State Beach through Tuesday, officials said, per SFGATE.

PEOPLE has contacted the Pacific Grove Police Department, the Monterey Fire Department, the U.S. Coast Guard, the Monterey County Sheriff’s Office and the California State Parks for further comment.