Police are investigating how an experienced sky diving instructor and his student fell more than 13,000 feet to their deaths and did not deploy their main parachutes at a popular southwest Florida camp.

Pasco County sheriff's authorities identified the victims as 41-year-old instructor Orvar Arnarson and 25-year-old student Andrimar Pordarson. The men were part of a group from Iceland, training and vacationing at Skydive City in Zephyrhills, Fla., on Saturday.

T.K. Hayes, general manager and president of Skydive City, said it appears Arnarson and Pordarson didn't activate their main parachutes.

"There's a multitude of scenarios. They lost track of altitude, weren't paying attention for whatever reason if they were distracted, most likely by something else going on. Who knows," Hayes said Sunday.

Both men had backup automatic activation devices, which deploy if the main parachutes are not opened in time. The backup chutes, the company says, did not fully inflate before they hit the ground.

The two men had successfully completed two other jumps Saturday morning with 20 other people. The men jumped separately, not in tandem. When Arnarson and Pordarson did not return from their third jump, Pasco County sheriff's department launched a search to look for the two skydivers.

Following a nine-hour search, the pair was finally located in a wooded area near Zephyrhills Municipal Airport, about a mile away from where they were supposed to land.

Authorities hope a camera worn by one of the men may give them some clues into what happened during the jump.

"We're reviewing the tape. We're reviewing anything that may have been said, on the camera," Pasco County Sheriff Chris Nocco said.

Last year across the U.S., 19 skydivers died out of 3.1 million jumps, according to the United States Parachute Association.

Arnarson was a seasoned veteran of the dare-devilish sport, who reportedly had thousands of successful jumps under his belt. For Pordarson, this was his eighth jump.

ABC News