CAIRO ― Thousands of Egyptians have vented their rage against President Hosni Mubarak's autocratic government for two straight days of protests that defied a ban on public gatherings. Baton-wielding police responded with tear gas and beatings in a crackdown that has shown no tolerance for dissent. Egypt's largest antigovernment protests in years echo the uprising in Tunisia, threatening to destabilize the leadership of one of the most important U.S. allies in the Arab world. The ability of the protesters to sustain the momentum for two days in the face of such a heavy-handed police response was a rare feat in this country. One protester and a policeman were killed Wednesday, bringing the two-day death toll to six. Some 860 people have been rounded up, and Facebook, Twitter and cell phones ― key to organizing protests ― have been disrupted. U.S. Secretary of State Hillary Rodham Clinton called on Egypt to adopt broad reforms and not crack down on the antigovernment crowds. She urged the Mubarak regime to “take this opportunity to implement political, economic and social reforms that will answer the legitimate interests of the Egyptian people.” Still, there was no indication that Mubarak, who has ruled with an iron fist for nearly 30 years, intends to relinquish power or make democratic or economic concessions, and no sign he would rein in his security forces. The defiant demonstrations continued late into the night Wednesday. In Cairo, dozens of riot police with helmets and shields charged more than 2,000 marchers on a downtown boulevard along the Nile. Smaller clashes broke out across the capital. In one, protesters stoned police, who responded with a volley of tear gas from a bridge over the Nile. One protester, businessman Said Abdel-Motalib, called the civil unrest “a red light to the regime. This is a warning.” In cities across Egypt, protesters incensed by Egypt's grinding poverty, rising prices and high unemployment hurled rocks and firebombs at police and smashed the windows of military vehicles. The Interior Ministry warned Wednesday that police would not tolerate any gatherings, and thousands of security forces were out on the streets poised to move quickly against any unrest. Many were plainclothes officers whose leather jackets and casual sweat shirts allowed them to blend in easily with protesters. Thousands of policemen in riot gear and backed by armored vehicles also took up posts in Cairo, on bridges across the Nile, at major intersections and squares, as well as outside key installations, including the state TV building and the headquarters of Mubarak's ruling National Democratic Party. Police fired tear gas to disperse a crowd of several hundred activists on a main thoroughfare, chasing them through side streets as both sides pelted each other with rocks while hundreds of onlookers watched. Plainclothes officers shoved some into waiting vans, slapping them in the face. Observing the clashes, Omima Maher, a 37-year-old housewife lamented her money woes. “Everything is so horrible. I hope we can change it,” she said. A policeman and a demonstrator were killed Wednesday when a car ran them over during a protest in a poor central Cairo neighborhood, security officials said. Earlier, three demonstrators died in clashes in the city of Suez and one policemen was killed in Cairo violence. In Suez, east of Cairo, a peaceful gathering turned violent at sunset when protesters threw rocks at a morgue where they were waiting for the body of a man killed a day earlier. Police broke up the crowd with tear gas, rubber bullets and live ammunition fired into the air. Women screamed as they called their sons home, and men vomited in the streets from the acrid white tear gas that filled the air. Protesters also firebombed the ruling party headquarters and a police station, damaging both buildings as burning trash littered the streets.