Protesters in Ukraine's capital extinguished burning barricades shielding them from the police on Thursday, enforcing a tenuous peace as an ultimatum issued by the opposition to the president was set to expire with no sign of compromise, AP reported. The fragile truce came after three main opposition leaders urged protesters late Wednesday to refrain from violence for 24 hours until their ultimatum to President Viktor Yanukovych expired. They demanded that he dismiss the government, call early elections, and scrap harsh anti-protest legislation that triggered violence at a demonstration on Sunday. Opposition leader Vitali Klitschko dove behind the wall of black smoke engulfing much of downtown Kiev on Thursday, pleading with both police and protesters to uphold the peace until the ultimatum expires Thursday evening. At Klitschko's request, protesters extinguished the burning tires that sent thick clouds of putrid smoke toward police lines. The largely peaceful protests against Yanukovych's decision to shun the European Union and turn toward Moscow in November descended into violence on Sunday when demonstrators, angered by last week's passage of repressive laws intended to stifle protests, marched on official buildings. For days protesters hurled fire bombs and stones at police, who retaliated with stun grenades, tear gas and rubber bullets. On Wednesday, riot police beat and shot at protesters, volunteer medics and journalists, resulting in the deaths of two demonstrators - the first casualties of the clashes. The opposition contended as many as five people died.