At least 25 people have been killed in Kiev as the Ukrainian capital plunges back into chaos. Rioters have attacked police, seized buildings, torched vehicles, and burned tires. Nine policemen are among the dead, all of whom died from gunshot wounds.

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Making public appeals to arm the opposition has crossed the line, declared Ukrainian President Viktor Yanukovich in address to the nation published on his website.

“This is a glaring violation of the law. The offenders must appear before a tribunal which will determine the measure of punishment for them. This is not my caprice, it is my duty as a guarantor of the Constitution - to ensure peace in the country, the peace of the citizens and justice for everyone,” the statement says.

The leaders of the opposition should immediately dissociate from the radicals provoking bloodshed and clashes with law enforcement, demanded Yanukovich.

“If they do not wish to abide, they ought to declare that they support the radicals. In that case they would be treated respectively,” the president declared.

Viktor Yanukovich said that opposition leaders demanded full power without elections, which is unconstitutional.

“I told the [opposition leaders] many times – elections are close. If people trust you, you will be in power. If they do not, you won’t. But both must occur legally, according to the Constitution of Ukraine,” Yanukovich stated.

During a phone call to Viktor Yanukovich, US Vice-President Joe Biden expressed “grave concern” at the surge of violence in the Ukrainian capital. Biden urged Yanukovich to exercise maximum restraint and pull back law enforcement confronting the rioters in downtown Kiev.

With the White House condemning violence in Ukraine, Biden maintained it is the special responsibility of Ukraine's government to defuse tension.

Biden also pushed “the urgency of immediate dialogue with opposition leaders to address protesters’ legitimate grievances and to put forward serious proposals for political reform.”

Ukraine's President Viktor Yanukovich and opposition leaders were unable to reach an agreement during the emergency meeting, RIA Novosti quoted UDAR party leader Vitaly Klitschko as saying. "Yanukovich said that there is only one option...to clear Maidan and that everyone has to go home," Klitschko told independent Hromadske TV after meeting with the Ukrainian president. It is not yet clear whether talks with the other two opposition leaders continued.

At least 11 protesters died in the riots, according to local officials. “As of 11 p.m. local time 221 people have sought medical attention, 114 of them were hospitalized. There were 11 fatalities,” Ukraine’s Health Ministry said in a statement.

The Ukrainian Interior Ministry reported that seven police officers died of gunshot wounds during the clashes. Two additional officers were later killed and another was critically injured as a traffic police unit was attacked in Kiev. The police officers died while in pursuit of the offenders.

The ministry added that 135 law enforcers have been taken to nearby hospitals, 35 of whom are in critical condition.

Kiev’s hospitals are unable to handle the large amount of injured people coming in from the streets, TSN reported. There is a wait for operation rooms and people are being carried in with various types of injuries. There have been reports of two amputations, punched out eyes, and injured extremities.

Thousands continue to occupy Kiev's Independence Square as state security forces move in to disperse the crowds.

Fighting in the Independence Square (Maidan) area has intensified, according to Twitter reports. Riot police are reportedly on the offensive, throwing stun grenades and spraying tear gas. Rioters are responding with Molotov cocktails. Gunshots can be heard.

Flashbangs and explosions have intensified at the #euromaidan. The feeling here is that the police might disperse the riot with force — Alexey Yaroshevsky (@Yaro_RT) February 18, 2014

Video footage of violence shows rioters pelting an armored personnel carrier with Molotov cocktails, setting it on fire. Reports from the scene say the fire has been extinguished and the vehicle is now operational.

Police used loudspeakers and urged protesters to leave Maidan. Speakers on stage are calling on the government to order its “dogs” (police) to leave them alone, and are chanting slogans like “Glory to Ukraine!” and “Death to the enemies!”

Russia’s Foreign Ministry issued a statement about the latest events in Kiev, saying that they are “a direct result of a policy of connivance" on the part of Western politicians. The ministry called the riots a “frank abuse of the rule of law and common sense.” It added that from the beginning of the crisis, Western politicians and European institutions have “turned a blind eye to the aggressive actions of the radical forces in Ukraine, thereby encouraging them.”

Earlier, a group of rioters armed with clubs stormed the Canadian Embassy in Kiev, according to the Interior Ministry's press service. The unidentified rioters reportedly broke into the embassy, destroyed some of its property, and attacked staff.

Another group of around 1,000 rioters attempted to storm a district police headquarters building in Kiev, using an explosive device in the process. The rioters seized two trolley buses in order to block streets and a truck which they used to ram police cordons. They also smashed an ambulance and broke into several offices in central Kiev.

German Foreign Minister Frank-Walter Steinmeier stated that Ukraine’s security forces have an obligation to de-escalate the situation.

FM #Steinmeier on #Ukraine: Security Forces have obligation to de-escalate. EU to reconsider restraint on sanctions against individuals. — GermanForeignOffice (@GermanyDiplo) February 18, 2014

UN Secretary General Ban Ki-moon has urged the Ukrainian government and opposition to show restraint and resume “sincere dialogue,” RIA Novosti quoted Ban's spokesperson, Martin Nesirky, as saying. "The Secretary-General is extremely concerned about reports received today regarding the resumption of violence and loss of life," he said.

Meanwhile, presidential adviser Hanna Herman told Radio Free Europe/Radio Liberty that talks between the government and the opposition are only possible when peace is restored. “Negotiations only happen when the force methods of fighting are stopped, when the opposition takes armed people off the streets and when calm is renewed in the country,” Herman said.

As the situation in Kiev intensifies, violence has been spreading to the west of the country. Hundreds of young rioters in the western city of Lvov seized the regional administration building and stormed the Lvov Central Internal Affairs Directorate, Interfax reported.

Rioters have also seized a military base, Ukrainian news website UA-RU.info reported. The protesters agreed with the military that troops would leave the base without weapons, and weapons warehouses have been sealed. A fire has engulfed the barracks. Thirty soldiers have been injured, five of whom were hospitalized, following the attack on the military unit, according to local police.

Around 300 rioters have also surrounded the local administration building and police department in the western city of Ternopol, Unian reported. Protesters threw bricks at the police department's windows and demanded that officers evacuate the building. As policemen began making their way out through the back exit, rioters continued to throw rocks and chased them down the street. There are reports that three smoke bombs and grenades were used.

Meanwhile, the southern Ukrainian Autonomous Republic of Crimea has urged President Viktor Yanukovich to come up with “decisive action and emergency measures” to end riots and restore constitutional order.

“The peaceful Crimea is extremely concerned with the latest surge of violence in central Kiev. The carnage on the capital’s streets proves that the opposition has taken manifold concessions on part of the government for a show of its weakness, and has used the amnesty law as a break before a new attempt of a forceful power grab,” Crimea’s Supreme Council said in a Tuesday statement.

According to the statement, the general mobilization – called by “extremist” groups like the Right Sector and the Svoboda Party – is nothing but the start of a civil war in Ukraine.