BAGHDAD, Iraq (AP) - U.S. Marines searching a Baghdad school made a chilling discovery: scores of black leather vests stuffed with explosives and ball bearings, along with empty hangers hinting that suicide attackers already might be outfitted to explode somewhere in this chaotic city.

More than 40 of the vests - on hangers and shrouded in plastic - lay on the floor of a classroom Saturday morning, two days after Marines discovered them in an elementary school in a middle-class neighborhood. Dozens of hangers were strewn on the ground outside the building.

''Odds are high that someone is out there wearing one,'' said Marine Lt. David Wright, 27, of Goldsboro, N.C. ''They were indeed dedicated to do something if they strapped on those vests.''

Just 150 yards away, a junior high school held hundreds of huge crates of weapons, rocket-propelled grenades, surface-to-air missiles and shoulder-launched rockets.

Residents of the neighborhood said members of the paramilitary Fedayeen came in about a month ago in pickup trucks in the middle of the night. The Fedayeen fighters unloaded the weapons in the two school compounds, yards from the nearest houses.

The residents said they had no idea what was being unloaded.

''We could not say, 'Don't put it here, don't put it there.' We couldn't prevent it,'' said Zina Selman, 45, whose house is less than 50 yards from the school with the apparent suicide vests.

The Marines discovered the weapons caches Thursday night. A reporter from The Associated Press was given a tour of them Saturday morning, as Marines continued to secure the compound to prevent residents of the middle-class neighborhood from entering.

U.S. troops in Iraq have been on high alert against suicide attacks.