Three members of Ukraine's National Guard have died from injuries sustained after a hand grenade exploded outside parliament amid protests over a bill that could give more autonomy to pro-Russian separatists.
The National Guard confirmed that 20-year-old Oleksandr Kostin died on September 1 in a Kyiv hospital from injuries sustained during the August 31 violence.
Interior Ministry Arsen Avakov earlier confirmed that a second member of the security force, Dmitry Slastikov, had died on September 1.
The first victim, 24-year-old National Guard conscript Ihor Debryn, died on August 31 after being hit by a grenade fragment while guarding the parliament building. Ninety other guardsmen were wounded in the incident.
Authorities say the grenade was thrown by a member of the nationalist Svoboda political alliance, identified as 27-year-old Ihor Humenyuk, as the government forces clashed with demonstrators.
Svoboda and the nationalist Radical Party organized the protest to voice opposition to legislation that could clear the way for pro-Russian separatists in eastern Ukraine to be granted more autonomy.
Investigators have summoned nearly 30 people for questioning, including Svoboda leader Oleh Tyahnybok, in connection with the clashes, the Interior Ministry said on September 1.
President Petro Poroshenko met with the country's top law-enforcement officers and called for a speedy investigation into the clashes.
Prosecutor-General Viktor Shokin said the perpetrators and organizers of the clashes would face lengthy prison terms on charges of carrying out a terrorist attack.
Parliament speaker Volodymyr Groisman urged all political parties on September 1 to condemn violence and rally around the president and his plans to devolve powers.
However, the Radical Party led by Oleh Lyashko said it would now officially oppose Poroshenko and his plan, which they believe threatens the country's sovereignty.
The bill, which was presented by Poroshenko and is part of Kyiv's obligations under the February Minsk peace accords, was tentatively approved by parliament on August 31.
It still requires approval by at least 300 of parliament's 450 deputies to be ratified as a constitutional amendment.
The protests on August 31 turned bloody after demonstrators learned that the legislation had passed its first reading.
Video footage that captured the grenade explosion showed more than a dozen riot troops limping after the blast, and at least one plainclothes officer falling to the ground and being dragged away.
Other footage showed bloodstains on the pavement and servicemen dragging away at least two other wounded guardsmen.
WATCH: Suspected Grenade Thrower Caught On Film
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Suspected Grenade Thrower In Kyiv Caught On Camera
It was the worst political violence seen in the Ukrainian capital since February 2014 when Euromaidan protests led to the ouster of President Viktor Yanukovych.
Authorities said a total of 30 protesters were arrested, of which 18 remained in custody as of September 1.
The demonstrators accused Ukrainian lawmakers of "capitulation to the Kremlin" after they gave tentative approval to the bill, which sets out the language of a draft constitutional amendment, which would clear the way for granting more autonomy to pro-Russian separatists in eastern Ukraine.
In a televised speech on August 31, President Poroshenko called the violence a "stab in the back."
"It was an anti-Ukrainian act for which all of its organizers without exception -- all representatives of political forces -- should be severely punished," Poroshenko said.
Prime Minister Arseniy Yatsenyuk blamed ultranationalists for the violence, which hospitalized more than 140 people including the wounded security forces and protesters.
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 April 2014.
He said that the protesters are trying to justify their violence "under the guise of patriotism."
World powers, including the United States, Germany, Russia, and European Union also have condemned the violence but welcomed the parliamentary action on the decentralization bill.
European Council President Donald Tusk said that, despite some domestic opposition, the legislation must be implemented before the year-end deadline stated in the cease-fire deal.
"I am concerned about the violence in Kyiv yesterday. In a sense, this shows the strong determination of the Ukrainian government and parliament to honor their obligations and implement the Minsk agreements," he said in a statement.
"It shows Ukraine is ready to pay a high price for peace," Tusk added.
Washington also added its voice of support.
"This action represents an important step toward comprehensive reform of Ukraine's governance and the empowerment of regional and local authorities," National Security Council spokesman Ned Price said.
The internationally brokered accords -- signed by Kyiv, the separatists, and Russia -- introduced a cease-fire and laid out steps toward a political solution to the conflict in eastern Ukraine.