Anti-militia protests show Libya's frailty (AP) BENGHAZI, Libya - Upheaval in Libya's second largest city raises a collision between Libyans' aspirations for change and the capability of the country's fragile, post-Muammar Qaddafi leadership to bring it. After protests against militias rock Benghazi, leaving at least four dead, residents on Saturday vowed a new "revolution" to rid themselves of armed factions and Islamic extremists. But authorities tried to stem the popular anger, pleading that with the police and army weak, they need some of those militias to keep security. Furious assaults by protesters against the compounds of several armed groups in Benghazi in the early hours Saturday were an unprecedented eruption of public frustration. Thousands stormed the headquarters of Ansar al-Shariah, an Islamic extremist group suspected in the Sept. 11 attack on the U.S. Consulate here. They drove out the Ansar gunmen and set fire to cars in the compound, once a major base for Qaddafi's feared security forces. The protesters then moved onto the base of a second Islamist militia, the Rafallah Sahati Brigade. Brigade fighters opened fire in rioting with the protesters. The state news agency Saturday said four protesters were killed and 70 injured during the night's turmoil. To watch Elizabeth Palmer's "CBS This Morning" report on the protests in Benghazi click on the video player below. Libyans storm militia in backlash of attack on U.S. Dispute over Libya attack; Witness tells CBS there was no protest Libya witness: Stevens was alive when found On Saturday, the city of 1 million in eastern Libya was brimming with anger, rumors and conspiracy theories. Some militiamen bitterly accused Qaddafi loyalists of fueling the protests. Further adding to the tensions, the bodies of six soldiers were found in the morning dumped on the outskirts of the city, shot through the forehead and their hands cuffed, state TV reported. An army colonel was reported missing, feared kidnapped. Some media reports accused militiamen taking revenge on Qaddafi-era veterans in the military; in contrast, a military spokesman, Ali al-Shakhli, blamed Qaddafi loyalists, saying they were trying to stir up trouble between the public and militias. Since Qaddafi's ouster and death around a year ago, a series of interim leaders have struggled to bring order to a country that was eviscerated under his 42-year regime, with security forces and the military intentionally kept weak and government institutions hollowed of authority. The militias, which arose as people took up arms to fight Qaddafi during last year's eight-month civil war, have typified the problem. They bristle with heavy weapons, pay little attention to national authorities and are accused by some of acting like gangs, carrying out killings. Islamist militias often push their demands for enforcement of strict Shariah law. Yet, authorities need them. The Rafallah Sahati Brigade kept security in Benghazi during national elections this year and guards a large collection of seized weapons at its compound, which was once a Qaddafi residence. Ansar al-Shariah protects Benghazi's main Jalaa Hospital, putting a stop to frequent attacks against it by gunmen.