KIEV, Ukraine -- Ukraine's festering political crisis took a deadly turn Tuesday, as thousands of anti-government protesters clashed with police outside Ukraine's parliament. Three protesters were killed in the melee, the opposition reported, and emergency workers found another person dead after a fire at the ruling party's office in Kiev.
Law enforcement agencies gave the demonstrators a deadline of 6 p.m. to stop the confrontations and vowed to restore order.
Dozens of protesters and police were injured in the clashes Tuesday, which broke out after opposition leaders accused pro-government factions in parliament of dragging their feet on a constitutional reform that would limit presidential powers -- a key opposition demand.
The clashes dimmed hopes for an imminent solution to the political crisis.
Tensions also soared following new steps by Russia and the European Union to gain influence over this former Soviet republic.
The protests began in November after President Viktor Yanukovych froze ties with the EU in exchange for a $15 billion bailout from Russia, but the political maneuvering continued and Moscow later suspended its payments. On Monday, however, while opposition leaders were meeting with German Chancellor Angela Merkel, Russia offered a fresh infusion of the billions of dollars that Ukraine needs to keep its ailing economy afloat.
As parliament delayed Tuesday's session to take up the issue, thousands marched toward the parliament building to put pressure on lawmakers. Shouting "Shame!" the demonstrators hurled stones at police and set trucks blocking their way on fire.
Riot police retaliated with stun grenades and fired what appeared to be small metal balls, as smoke from burning tires and vehicles billowed over Kiev, the capital.
Three protesters died in the clashes, Oleh Musiy, a top medic for the protesters, told The Associated Press. Opposition lawmaker Lesya Orobets made the same statement on Twitter.
About 150 protesters were injured, the protesters' medical unit said, while the Interior Ministry said about 40 officers had been hurt.
Justice Minister Olena Lukash, a close Yanukovych aide, accused the opposition of violating earlier agreements with the government and blamed protest leaders for the violence.
Earlier in the day, protesters stormed the office of the president's Party of Regions, but police pushed them away. When firefighters arrived to put out a fire, they discovered the body of an office employee, Kiev's emergency services said in a statement.
Tuesday's confrontations came two days after the government and the opposition reached a shaky compromise, with protesters vacating a government building in Kiev they had been occupying since Dec. 1 after the government released of scores of jailed activists.
But tensions rose after Russia's finance minister offered to resume financial aid to Ukraine on Monday, just as Yanukovych was expected to nominate a new prime minister, prompting fears among the opposition that he would tap a Russian-leaning loyalist.
"After weekend progress in Kyiv, sorry to see renewed violence," U.S. Ambassador Geoffrey R. Pyatt said in a Twitter post. "Politics needs to happen in the Rada (parliament), not on the street."
Opposition leader Vitali Klitschko called on Yanukovych to agree to the reforms and to call an early election or face a serious escalation of the crisis.
"We are talking minutes, not hours," Klitschko told reporters.
Yanukovych still remains popular in the Russian-speaking eastern and southern regions of Ukraine, where economic and cultural ties with Russia are strong. But western Ukraine is keen to pursue closer ties to the 28-nation EU and move away from Russia's orbit.
Russian President Vladimir Putin promised Yanukovych $15 billion in loans in December, but after purchasing Ukrainian bonds worth $3 billion Russia put the payments on hold. The Russian finance minister said Monday that $2 billion more would be purchased this week.