SALT LAKE CITY (AP) — The father of 14-year-old Elizabeth Smart, who was reported kidnapped from her home six days ago, was given a lie detector test, police said Monday.

"Ed did submit to a polygraph yesterday and that's being reviewed by the FBI," Salt Lake City Police Capt. Scott Atkinson said. No one else has been given the test, Atkinson said.

Police won't say why they asked Edward Smart to take the polygraph, but Detective Jay Rhodes said "it's not uncommon" for police to administer such tests to parents of missing children.

Also Monday, Elizabeth's uncle Tom Smart asked for 40 or 50 all-terrain vehicle owners to gather near an exit off Interstate 80 west of Salt Lake City to help search the desert.

He said there was no specific information that prompted the plan to search in the area.

"We take nothing for granted in this and we want to search every inch of this state and beyond," he said. "We'll try to have a plan of attack for as many days as we need to go."

Police said they are baffled by the case.

Elizabeth disappeared early Wednesday, abducted from her bedroom in the family's $1 million home bordering a wooded area in the city's Federal Heights area, authorities said.

A man brandishing a small black handgun entered the bedroom shared by Elizabeth and her 9-year-old sister, authorities said last week. The man forced the older girl to go with him and told the younger girl that if she told anyone, her sister would be hurt, the child told police. She waited about two hours or more and then woke her parents, police said.

Eleven volunteer pilots took their planes up Sunday, down from 25 the day before. They looked for any clues that might help the investigation, though the number of weekend campers in nearby mountains made it difficult to locate anything considered suspicious.

"It's becoming a very expensive proposition," said Jamie Guttierrez of Angel Flight, which provides charitable air services. "Each one of those pilots is pulling out $300 a day from his own pocket for flight costs."

Search efforts suffered another setback when two helicopters equipped with infrared-sensing equipment were diverted to help battle wildfires in Colorado.