UPDATED: 7:15 p.m. ET / Feb. 18, 2014

KIEV, Ukraine — At least 22 people were reported killed on Tuesday in what was by far the bloodiest day of violence in the Ukrainian capital of Kiev since mass protests and civil unrest began in late November .

Clashes between police and protesters began only a block away from the Verkhovna Rada, the country’s parliament and continued throughout the evening. Protesters fought with bats, Molotov cocktails, rifles and paving stones; riot police fired rubber bullets, and in some cases, live ammunition.

By nightfall, thousands of protesters gathered and lit blazes in Independence Square.

The death toll included two police officers who were shot to death chasing a car with suspected criminals. Altogether, according to the Kyiv Post newspaper, seven policers officers died in the violence. Fifteen protesters were killed and an estimated 1,000 were injured.

One protestor suffocated in smoke at the Party of Regions office; three other dead bodies were found at the Officers' House (two with gunshot wounds and one with road accident injuries); another died in an ambulance, also from a gunshot wound; and two more died from heart attacks, Kiev police told Interfax-Ukraine news agency.

The two policemen also died from gunshot wounds, one in an ambulance and the other in the hospital, police said.

Just before midnight on Tuesday, city lights went out in central Kiev and around Indpendence Square. Shortly afterward police and so-called titushki, or thugs for hire, fired ultraviolet paint pellets at protesters to illuminate them in the darkness.

Oleksandr Turchynov, an opposition leader and former deputy prime minister in the government of jailed former Prime Minister Yulia Tymoshenko, was wounded while speaking from the main EuroMaidan stage of Independence Square. It's unclear exactly what struck him, but several news outlets reported that he was hit in the face and received medical attention.

Opposition leaders Vitali Klitschko and Arseniy Yatseniuk met with President Viktor Yanukovych after midnight to discuss possible solutions to the unrest. Speaking to Hromadske TV, Klitschko said that he left negotiations first, followed by Yanukovych, without coming to an agreement.

According to Klitschko, the meeting lasted for more than an hour, during which time he and Yatseniuk listened to accusations from the president that the opposition is to blame for the deaths of Ukrainians on the streets. Yanukovych's solution, he added, was for protesters to "quit everything ... and go home."

Riot police managed to break through a second-floor window of the Trade Unions building and occupy most of its floors. The building has been used for more than two months as the headquarters of the anti-government protest movement, called EuroMaidan.

A session was set to take place there this morning in which opposition lawmakers hoped to pass amendments to the constitution that would curb the powers of the president. However, it was cancelled due to the violence outside. In the video below, taken by Mashable's correspondent on Feb. 18, shows protesters heaving tear gas into a group of police. (A live video feed is embedded below.)

The struggle began after dozens of protesters managed to break through a police cordon comprised of four large military trucks. They managed to release the emergency brake of one of the trucks and push it aside. Protesters hurled stones and Molotov cocktails at police, who in turn heaved tear gas and noise grenades at the group. At least five police, including two snipers, were seen atop a nearby building, throwing down tear gas at protesters, firing metal pellets and using the high vantage point to single out the most radical of participants.

Late Tuesday afternoon local time, the Security Service of Ukraine and the nation's interior minister released a joint statement saying authorities were prepared to use all means available against protesters if the violent clashes do not end by 6 p.m.

“If by 6 p.m. the lawlessness doesn't cease, we shall be forced to used all legal means to bring order,” said acting head of the Security Service of Ukraine Oleksandr Yakymenko and acting Interior Minister Vitaliy Zakharchenko.

In addition, a prominent ally of Yanukovych, oligarch Rinat Akhmetov, said in a statement posted to the website of his company, System Capital Management, that today's killings were an "impossible price for political mistakes."

"The bloodshed must end and negotiations restart immediately," Akhmetov said. "There are no circumstances that justify the use of force against the civilian population."

Several protesters received injuries as a result of hand-to-hand combat and sniper fire. One young man was shot in the eye. Bleeding profusely, he was taken to an ambulance by medical personnel. At least two police officers were severely beaten by protesters wielding metal pipes and baseball bats when they were separated from their group. One lost consciousness briefly before being attended to by medics.

This protester was just shot in the head with rubber bullet, presumably fired by police sniper. #kyiv #ukraine pic.twitter.com/LixNexK7Kj — Christopher Miller (@ChristopherJM) February 18, 2014

Protesters shattered the windows of the police trucks before dousing them in gasoline and setting them ablaze. Flames several feet high raged for more than an hour and thick, black smoke billowed into the sky.

Thousands of demonstrators looked on, chanting “out with the gang” and “convicts out,” referring to pro-government lawmakers from the Party of Regions and the president, who was twice convicted of assault crimes in his youth. Some protesters dug up paving stones from sidewalks and passed them to a human chain that sent them to protesters fighting with police on the front lines. One block away, another group of protesters, led by activist Tetyana Chornovol, who was badly beaten in an attack in December, broke the windows and doors of the ruling Party of Regions Kiev headquarters in an attempt to storm the building. Those inside countered by showering protesters with water from a firehouse out the second-floor window. Protesters inside two of the windows heaved Molotov cocktails, igniting small fires that were quickly put out. One person inside the building tossed glass bottles at the mob outside. Within 30 minutes, police arrived on the scene, beating back the crowd with tear gas and blunt force. They eventually managed to cordon off the building and repel protesters from the street. The protesters set up their own cordon about 160 feet away, in case police should try to attack protesters near the parliament from behind. Eventually, a group of police did attack from behind, storming out of a building half a block from the site of the first clashes near parliament. The violence continued into the afternoon, as the number of protesters and police on the streets increased.

Ukraine's Interior Ministry reported that 37 police officers have been injured in the clashes, thus far, according to a statement posted to its website. Some suffered wounds from BBs. In a post on Twitter, opposition lawmaker Lesya Orobets wrote that three protesters had died as a result of the clashes. Their bodies were transported to the House of Officers, two blocks from the site of the main clashes. Dr. Olga Bogomolets, a well-known physician and the head doctor for the anti-government protest movement, confirmed the death of three protesters. The clashes come almost one month to the day of a battle between police and protesters on another central street, Hrushevskoho. From Jan. 19 to Jan. 23, the two groups fought around the clock. At least five protesters were killed as a result, and several hundred on both sides were badly hurt.

On Tuesday, more than 1,000 protesters went back to the street and reinforced barricades erected in January. There, they burned tires to create a smokescreen and keep police from advancing. The public unrest in Ukraine began last November, when President Yanukovych spurned a long-anticipated deal with the European Union, and instead turned to Russia for a $15 billion bailout. Russia seeks to pull Ukraine into its political orbit, while the EU would like to see the former Soviet country move westward.

By nightfall, many thousands of protesters had converged on Independence Square, the heart of the Euromaidan protests since November. Fires were stoked with tires and Molotov cocktails. Below is a live video feed from the square, provided by Espresso TV:

Photos From the Ground