(atomische's flickr)

One man has died and another is clinging to life this morning after the pair were found at the bottom of the "adult lap swim" area of a public pool in Staten Island. The two men, described as "strong, muscular, strapping young men," were found around 8:30 a.m. at the bottom of the crowded Lyons pool. Both went into cardiac arrest after being pulled out of the water and being taken to Richmond University Medical Center. One was pronounced dead upon arrival.

It is unclear exactly what the men, who are said to be in their 20s, were doing at the bottom of the pool but at least one witness says they were doing some sort of training exercises. A law enforcement source told the Advance that a group of four men were going under water, two at a time, and had been at the pool every weekday morning since the public pool in Tompkinsville opened in June.

"What happened today is they were doing some sort of underwater breath-holding exercise," a witness told the Post. "The lifeguards were beside themselves. They were giving them CPR. When they pulled them up, they were limp," Ellison added.

The pool, located on Victory Boulevard, opens to the public at 7 a.m. and was fully staffed and "crowded with swimmers" at the times of accident. Parks Department Commissioner Adrian Benepe is scheduled to hold a press conference at the pool later today, according to an agency spokeswoman.