Beirut - Lebanese riot police fired tear gas and water cannons for the second consecutive day in downtown Beirut on Sunday as they battled protesters with batons and stones - a marked escalation of mass demonstrations against an ongoing trash crisis.The violence came hours after Prime Minister Tammam Salam hinted he might step down following violent protests on Saturday that injured more than 100 people. The violence threatened to plunge Lebanon in new instability and political turmoil, adding to the greater Mideast's upheaval.The demonstrations, the largest in years to shake tiny Lebanon, seek to upend what protesters see as a corrupt and dysfunctional political system that has no functional Cabinet or parliament, nor a president for more than a year.Sunday's clashes broke out shortly before sunset when angry protesters tried to break through barbed wire leading to the government's headquarters. Police beat back protesters with clubs and water cannons, occasionally hurling stones at protesters who threw rocks and water bottles.At least two riot police officers were injured and whisked away by their colleagues. Ambulances carried away at least five injured protesters from Riad Solh Square in central Beirut, where the demonstrators had been gathering since the morning.Later on Sunday evening, protesters were able to break through the first barbed wire after intense clashes with security forces. When the protesters got closer to the government headquarters, police fired tear gas, forcing thousands to flee.The protesters took over a police motorcycle and set it on fire. Some protesters carrying clubs also attacked police vehicles, hurling stones and bottles at them."Shabiha!" the protesters would shout, an Arabic term often used to refer to thugs.Some of the protest organizers suggested that radical elements had infiltrated their peaceful protest for political gains.The protests started over garbage piling up on the streets after the capital's main landfill was closed a month ago. An online group calling itself "You Stink!" and other civil society groups organized the rallies, calling on Lebanese to join them in a revolt against the corrupt system.Protesters now demand that the country's top politicians resign, saying they are not fit to rule to country. Salam, Lebanon's prime minister, said in a news conference earlier Sunday that if this Thursday's Cabinet meeting is not productive, "then there is no need for the council of ministers."Lebanon has a sectarian power-sharing system that ensures equal representation between the country's main religious sects. The arrangement often leads to complete paralysis. A resignation by Salam would risk plunging the country into further chaos.