Investigators are having the burned-out boats from a massive marina fire at Lake Powell towed to a secure area where they will be examined in an effort to determine the fire's cause, the National Park Service said.

The Utah State Fire Marshal's Office and agents from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives were at the Hall's Crossing Marina on the border of Kane and San Juan counties over the weekend examining what's left.

"What they said basically is that because of the environment, the widespread damage and the fact that it's a marine environment, it's probably going to take quite a while to pinpoint the specific cause," Max King with the Glen Canyon National Recreation Area said Monday.

The fire originated on F dock, which is now pretty much destroyed, on Thursday around 11 p.m., King said. The fire spread to one side of the D dock. Approximately 15 boats were destroyed in the blaze. Firefighters were able to save about 130 boats moored at the marina.

"There was a lot of potential for much, much more serious damage," King said.

The owners of many boats shared information and offered to help each other in comments posted online at deseretnews.com. "My wife feels like we have lost one of the family," wrote one. "All that is left of my boat is the front deck and rear deck and there is a big burned out hole in between." "I can tell you the fire was bad with propane tanks and gas tanks ...," wrote one person who helped fight the fire.

"Thank you to everyone trying to save our boat and others. You are really heroes to risk your lives for our pleasure," wrote another. "I feel very blessed to have you guys looking out for all of us and can't thank you enough for keeping the damage to the few instead of the whole marina." Three boats sank in the fire, including one believed to be in water 200 feet deep. Damage altogether is estimated at about $5 million. The state fire marshal has still categorized the fire's cause as unknown. The ATF was involved because Glen Canyon National Recreation Area is a federal facility.

Authorities won't begin examining the wreckage in earnest until after the new year, King said. Anyone with information regarding the fire can call the Utah State Fire Marshal's office at 801-284-6350.

E-mail: bwinslow@desnews.com