Security police at Andrews Air Force Base, training dogs to find explosives, hid two sticks of live dynamite on Thursday in the wheel well of a tan Datsun pickup truck parked on the base.

The dogs did not find the dynamite. And for more than 12 hours, no one else could either.

Meanwhile, the owner of the pickup truck -- blissfully unaware that explosives had been tucked under his car -- drove throughout Prince George's County, traversing roads from Camp Springs to Upper Marlboro to Bowie, sources familiar with the incident said.

"Live dynamite was placed on random vehicles parked near the explosives training site," said Capt. Gail Bennett, deputy chief of public affairs for Andrews. "Basically, the vehicle owner, not aware that the training was taking place and that the explosives had been placed on his vehicle, departed the base."

Base authorities found one stick of dynamite, which apparently fell off the truck, near the base gate. The other stick of dynamite is still missing.

As for the owner of the pickup, Andrews authorities finally located him about 8 a.m. yesterday after frantically trying to trace his out-of-state license plate. Base officials identified the man only as a retired military officer who recently moved to the Washington area and was conducting business on base Thursday.

Authorities surmised that the second stick of dynamite fell off the pickup truck somewhere during the man's travels about the county.

Base officials issued a terse news release yesterday asking for public assistance locating the missing explosive, an 8-inch cylinder, wrapped in orange material and labeled "Ditching Dynamite." The release urged caution.

The man, Bennett said, parked adjacent to the explosives training area on Thursday and "was not in the area when the training aid was placed on his vehicle."

"He was not advised that the training aid had been placed on his vehicle . . . . However, the training area was clearly marked with signs stating that explosives training was in progress," Bennett said.

Base officials said they realized the dynamite was missing about 6 p.m. Thursday.

Prince George's County police and Maryland State Police were contacted about an hour later and told to look for a tan Datsun pickup truck with a Kansas license plate, sources said.

"All we can say right now," Bennett said, "is that there still are a lot of questions to answer."