The United States has voiced condemnation of the bloody crackdown on anti-coup activists in the eastern Ukrainian city of Mariupol, blaming Russia for inciting the violence there, US State Department spokeswoman Jen Psaki has said.

"We condemn the outbreak of violence caused by pro-Russia separatists this morning in Mariupol, which has resulted in multiple deaths," she said. "We continue to call for groups who have jeopardized public order by taking up arms and seizing public buildings in violation of Ukrainian law to disarm and leave the buildings they have seized."

Psaki said that the US is watching very closely over the developments in Mariupol.

"Any steps Russia would be willing to take to defuse tensions in accordance with its Geneva commitments," the spokeswoman added.

"We've seen their words before. What we're waiting for is actions, and if this crisis is going to end, we need their words to be made real," Psaki said referring to President's Putin's recent call for a direct dialogue between Kiev and anti-coup protesters in southeast Ukraine as a key measure to ending the crisis.

"So if they are serious about what they're saying, they need to tell separatists to lay down their arms, to release those who are being held, and that, obviously, we have not seen happen," Psaki added.

As reported, on May 9, the Ukrainian servicemen tried to storm the police department building in the town of Mariupol of Donetsk region where policemen, who had refused to obey orders from Kyiv, had barricaded themselves in.

A fire broke out and the department building burned to the ground.

In all, seven people died and 39 sustained injuries in the army operation in Mariupol, the regional administration's health department said.

Ukrainian Interior Minister Arsen Avakov said one law enforcement officer died and five were injured in the fighting. He claimed the death of about 20 militiamen and the capture of four.