At least 27 people were injured on Friday when a series of blasts hit Ukraine just weeks before it is due to co-host the Euro 2012 football championship.
Authorities said they were treating the attack as an act of terrorism.
The blasts went off in quick succession around noon in the eastern city of Dnipropetrovsk, targeting a tram stop, a cinema and a railway station. Witnesses said it appeared that explosive devices had been placed in nearby rubbish bins. Authorities said at least four blasts had gone off, but some reports placed the number as high as 10.
Ukraine has no history of modern terrorism and it was unclear who could be behind the blasts. The attack will raise concerns as Ukraine gets ready to host Euro 2012 from 8 June. Dnipropetrovsk lost its bid to host a match, but nearby Donetsk is one of the championship's main sites.
Dnipropetrovsk is the birthplace of Yulia Tymoshenko, the former Ukrainian prime minister who is currently in jail on charges of abuse of power that she insists are politically motivated by her chief rival, President Viktor Yanukovych. He has denied the accusation. Tymoshenko launched a hunger strike last week to protest the conditions under which she is being held.
Commenting on the blasts, Yanukovych said: "We understand that this is yet another challenge for us, for the entire nation."
"We don't know why this would have happened," said Cole, who has been living in Ukraine since August. "It's dead outside – all you can see is police officers and medics. I've never heard the city so quiet."