A report that two men were spotted driving a U-Haul truck loaded with bomb components prompted an intense search Monday, but hours later it appeared the episode resulted from a misunderstanding.

By Monday night, FBI agents had identified the two men driving the truck and determined their cargo was legitimate, but the truck had not been located and agents wanted to interview the men to be sure, according to media reports.

Federal authorities said a witness told police the men were loading diesel fuel into containers in the back of the truck with out-of-state license plates at a Texaco station Saturday. Local police said at a news conference that the witness saw three men at the station in Haltom City, a suburb north of Fort Worth.

Someone else at the station observed that the truck held three blue plastic containers that appeared to be filled with ammonium nitrate fertilizer, the FBI said.

The materials spotted in the truck could produce an explosion big enough to destroy a large building, the FBI noted in an advisory.