MONROVIA, LIBERIA, SEPT. 28 -- A weeklong cease-fire collapsed today when government troops and rebels battled for several hours in this capital.

Artillery and machine-gun fire erupted before dawn. Government forces fired at random from the presidential mansion where up to 1,000 followers of the late president Samuel Doe have been trapped between rival rebel factions.

The fight began Thursday afternoon when rebels led by Prince Johnson discovered a large government arms cache in a central warehouse near the Defense Ministry. Government forces tried to retrieve the weapons but were repelled by Johnson's fighters.

When five truckloads of captured rocket launchers, mortars and ammunition were brought in to Johnson's base, a witness described the rebel leader as "exuberant."

"Now I'm ready for Taylor. Now I'm going to get him," he quoted Johnson as saying.

Charles Taylor, who heads the biggest rebel group, warned Thursday that he would annihilate Johnson's followers as well as the 6,000 members of a five-nation West African peace-keeping force.

Taylor, who has proclaimed himself Liberia's new leader, said on radio: "If this war has to be fought for the next 10 years, we must be prepared because, as the president of Liberia, I am prepared to devote the next 10 years of my life to hunting these bandits until they leave."

Taylor derided members of the peace-keeping force as thieves, rogues and hooligans, saying, "We will keep killing them until they realize they must go."

About 1,500 reinforcements, mostly Nigerian troops, arrived Thursday with the West African force's new commander, Nigerian Gen. Joshua Dogonyaro, who toured the war-torn capital today in a long motorcade of tanks and armored personnel carriers.

The Associated Press reported that a Nigerian freighter carrying 150 tons of rice, canned food and cooking oil was unloaded in port today. It was the first major food shipment since July to reach the capital, where even the most basic of foodstuffs are in scarce supply.