GOMA, Congo (AP) - Crowds of protesters threw rocks outside four United Nations compounds in eastern Congo on Monday, venting outrage at what they claimed was a failure by peacekeepers to protect them from rebel forces advancing on the provincial capital of Goma.

People in eastern Congo are furious that the 17,000-strong U.N. peacekeeping force has been unable to protect them from a rebel force which says it is fighting to protect ethnic Tutsis. Residents opposed to rebels, including Hutus and those who lived in camps after fleeing earlier conflicts, feel particularly threatened. Tens of thousands of civilians have abandoned their homes.

The crowds shattered windows and damaged cars at the main U.N. office, U.N. spokeswoman Sylvie van den Wildenberg said. One witness said he saw a peacekeeper fire into the crowd at one compound and injure a man, but it was not immediately possible to confirm the report.

Hundreds of soldiers pulled back from the front just 40 kilometers (25 miles) north of the city in tanks, jeeps, trucks and on foot in what appeared to be a major retreat. Soldiers honked their horns angrily as they struggled to push through throngs of displaced people poured onto the main road.

The civilians and soldiers pushed south from a major army base seized by the rebels and surged toward the provincial capital of Goma. Rebel leader Gen. Laurent Nkunda has threatened to take Goma in defiance of calls from the U.N. Security Council for him to respect a U.N.-brokered January cease fire.

As the crowds surged within reach of the city, soldiers blocked access to the northern entrance of Goma, apparently fearing that rebels could be trying to infiltrate with the displaced civilians.

Women and children lay down on roadsides made muddy by tropical downpours, stretching out to spend the night. Some had mats or plastic sheets; others simply dropped, exhausted, to the earth.

Rebel spokesman Bertrand Bisimwa claimed in an interview with The Associated Press that fighters were within 12 kilometers (seven miles) of Goma. Residents of Katindo, a neighborhood five kilometers (three miles) from downtown Goma told The Associated Press they heard bombs exploding late Monday afternoon.

Inside Goma, terrified and angry civilians converged on U.N. offices, all of which are located within the compact city. One witness, Emmanuel Kihombo, said a peacekeeper fired directly into the crowd at one compound and shot a man in the stomach.

Kihombo, who is unemployed, said the protesters also hurled stones at about 20 Tutsi students, but that they all managed to run away.

It was an indication of dangerously building anti-Tutsi sentiment fueled by the success of Nkunda's rebels, who say they are fighting to protect minority Tutsis from a Rwandan Hutu militia that escaped to Congo after helping to perpetrate the 1994 Rwandan genocide. Half a million Tutsis were slaughtered.

Congo's government has accused the Tutsi-led government that won power in Rwanda after the genocide of sending troops to support Nkunda - a charge Rwanda denies and the U.N. says is unfounded.

U.N. officials said Nkunda's fighters on Sunday blatantly launched several rockets at two U.N. armored cars. A spokesman for Nkunda denied responsibility for the attack that injured several U.N. soldiers and damaged the cars.

Van den Wildenberg, the U.N. spokeswoman, said there was no doubt the attack came from Nkunda's rebels. She said the peacekeepers were trying to get to thousands of people still trapped behind the front line around Rumangabo, the strategic army camp north of Goma.

Nkunda's rebels overran the camp early Sunday and retained it - despite soldiers pounding the area with heavy artillery from tanks and smaller armed vehicles.

A U.N. official told The Associated Press its commanders were considering using helicopter gunships to attack the rebels, but that the logistics were difficult. Adding to the confusion, rebels are attacking on several fronts and retreating to banana plantations, passing frightened civilians trying to get away, according to the official, who spoke on condition of anonymity because of the sensitivity of the subject.

The last time Nkunda's fighters marched on Goma, in December, peacekeepers fired on them from attack helicopters, killing hundreds of rebels under their mandate to protect civilians.

The ragtag Congolese army, cobbled together of defeated army troops and several rebel and militia groups after back-to-back wars from 1997-2003, is disjointed, undisciplined, demoralized and poorly paid with lowest-ranking troopers getting little more than $20 a month.

Nkunda is believed to command about 5,500 highly trained and disciplined fighters.