Four blasts within minutes have rocked the centre of the Ukrainian city of Dnipropetrovsk, injuring at least 27 people, including nine schoolchildren.
Prosecutors are treating it as a terrorist attack.
The first blast occurred at a tramway stop in the city centre, injuring 13 people.
The second injured 11 people near a school, among them nine children, while the third wounded three near a railway station.
A fourth blast was also heard in the city centre but it was unclear whether anybody was injured.