Fears that fuel was leaking from three Minuteman rocket motors prompted the evacuation of an elementary school, youth center and some homes on Hill Air Force Base Tuesday afternoon.

Around 2 p.m., the drivers of the tractor trailer truck carrying the rocket motors to the base from North Dakota arrived at the southwest gate and reported that fumes in the truck had made them feel ill, said base spokesman Len Barry.Air Force experts immediately started an investigation, Barry said.

As a precaution, 727 children were evacuated from Hill Field Elementary School around 3 p.m. and taken to Clearfield Elementary. The children were in no immediate danger and none appeared to have been exposed to any fumes, said Davis County School District spokeswoman Sandra Wilkins.

The base youth center and an undisclosed number of residences were evacuated along with the elementary school. The evacuation ended around 4:30 p.m., Barry said.

Though base officials still do not know what the fumes were that nauseated the drivers, they have ruled out rocket fuel leakage, Barry said.

"Our preliminary investigation showed no leak from the rockets whatsoever," he said.

The truck engine could be the source of the fumes. "That's just one possibility, though," Barry said, adding that the investigation is continuing.

The drivers were examined at the scene and one was taken to the base hospital for observation. Both were in good condition, the spokesman said.