World powers have condemned deadly violence outside Ukraine's parliament and urged legislators to keep up their work decentralizing the government through measures that implement the Minsk cease-fire agreements.
Statements of concern from the United States, Germany, Russia, and the European Union came as Ukrainian Prime Minister Arseniy Yatsenyuk blamed ultranationalists for the violence, which left at least 122 injured and killed two Ukrainian national guardsmen.
In an address on live television, Yatsenyuk said the right-wing protesters were "worse" than the Russian-backed separatists in eastern Ukraine who have been locked in a civil war with the government since last year, because their violence comes "under the guise of patriotism."
"At a time when Russia and its bandits are seeking to destroy the country but are unable to do this on the front line, the so-called pro-Ukrainian political forces are trying to open a second front inside the country," Yatsenyuk said.
He called for life imprisonment for the protester who threw a grenade that killed the guardsmen.
WATCH: The Suspected Grenade Thrower Caught On Camera In Kyiv
World powers deplored the violence and urged Ukrainian leaders to forge ahead with constitutional changes aimed at carrying out pledges in Minsk to grant more power to local governments, including those in eastern Ukraine.
"Street violence is unacceptable under any circumstance, but violence against the decisions of an elected parliament is even more so," the German foreign ministry said.
"In a democratic society, grievances must be addressed peacefully and lawfully," said deputy U.S. State Department spokesman Mark Toner. "We call for a full investigation into the cause of today's violence. Those responsible should be held accountable."
"Today's events are very worrying," said EU foreign-affairs head Federica Mogherini, adding that the legislative "process shouldn't be jeopardized by violence."
Kyiv's Western allies see the reforms as a chance to end the armed conflict in the east that has claimed more than 6,800 lives over the past 16 months.
Mogherini said the constitutional amendments legislators approved in an initial vote "will facilitate the implementation of the Minsk agreements" by taking "an important step that paves the way towards a substantial devolution of powers from the central level to regions and communities."
Mogherini said the EU wants the Ukrainian parliament to continue adopting the decentralization amendments in a final reading later this year, as well as continuing work on judiciary-related constitutional amendments.
In the initial vote, 265 legislators supported the reforms. Three parties that are part of the majority coalition in parliament refused to give their support, showing the difficulty that Ukrainian President Petro Poroshenko faces even within his own pro-Western camp in fulfilling the peace agreement.
In the second reading, which is expected by the end of the year, the amendments will require a two-thirds majority of at least 300 lawmakers to pass.
The EU is confident, Mogherini said, that "Ukraine will stay firmly on its way to further reforms, both institutional and economic, as well as a comprehensive reform of the police and the law enforcement sector to ensure public order and safety across the country."
The Organization for Cooperation and Security in Europe's Parliamentary Assembly President Ilkka Kanerva said that "the last thing that Ukraine needs is more blood spilled on its soil and more destruction."
While the constitutional changes are "tough and emotionally charged," he said, "they have a direct bearing on war and peace and commitments under the Minsk agreements. Broad national dialogue and work through democratic channels is what is needed, not bombs."
A Kremlin spokesman also condemned the "displays of violence," but dismissed the legislative reforms as only an "imitation" of compliance with the February peace deal.
Russia has been demanding that the Russian-speaking regions in Ukraine's east, which have been demanding autonomy, have their special status spelled out in constitutional amendments that would be very hard to overturn.