The United States has warned Russia that it would be a "grave mistake" to embark on military intervention in Ukraine.
"I don't think there should be any doubt whatsoever that any kind of military intervention that would violate the sovereign territorial integrity of Ukraine would be a huge - a grave mistake," US Secretary of State John Kerry said.
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The families of all four of the victims, all of whom were men, have been informed, police said.
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AC/DC co-founder and ex-guitarist Malcolm Young has died aged 64, his publicist has announced.