(CNN) -- A skydiving instructor on a tandem jump in Mississippi died and his student was critically injured after their parachutes failed to open, the Lamar County sheriff said Sunday.
The body of James "Jimmie" Horak, Jr., 66, was found Saturday in heavy mud in a swampy wooded area about a mile from the airport in Lumberton where they planned to land, Sheriff Danny Rigel said. The other person, whose name was not released, was in critical condition with broken bones and head injuries.
Horak and the student were with a group of three others who jumped from the plane at the same time around midmorning Saturday, under sunny skies, Rigel said. Horak and the student were the only ones doing a tandem jump.
The others noticed that Horak had had some kind of equipment trouble -- perhaps a problem with his lines -- but didn't appear to realize how serious it was until after they landed at the airport and the pair didn't emerge from the woods, Rigel said.
Horak and the student landed on leased hunting land, and a hunting club member who knew the jumpers were missing then found them, Rigel said.
Deputies had to carry Horak and the student for a "considerable distance" to get them out of the woods, and the student was then airlifted to Forrest General Hospital in nearby Hattiesburg, Rigel said.
The Federal Aviation Administration will inspect the parachutes to determine if they were properly rigged by a qualified parachute rigger, and if the parachute operation was in compliance with federal regulations, FAA spokeswoman Kathleen Bergen said.
Local authorities will investigate the event and determine probable cause, she said.
Horak's cause of death won't be known until after an autopsy, likely to take place Monday, Rigel said.
Horak, of Pensacola, Florida, is listed as an instructor with the Emerald Coast Skydiving Center in Elberta, Alabama, just across the Florida-Alabama state line. A different skydiving company, Gold Coast Skydivers, is based at the airport in Lumberton where Horak was supposed to land.
It wasn't immediately clear who organized Saturday's jump. Neither company could be reached for comment Sunday.