A series of bomb blasts rocked Dnepropetrovsk city in eastern Ukraine Friday afternoon, injuring at least 27 people, local media said, without specifying the number of explosions, Xinhua reported.
The Interfax-Ukraine news agency, referring to its own sources, said 25 of the injured were hospitalized.
Police officers were searching for other explosive devices in the city center, Interfax-Ukraine said.
Emergency authorities meanwhile reported 25 people were injured in four separate blasts in Dnepropetrovsk.
An explosive device went off at a busy streetcar station at 11:50 am local time (0950 GMT), injuring 13 people and causing panic among those in the vicinity, according to the ministry.
Half an hour later, an unknown object exploded in a garbage can near the central cinema, injuring 11 people, including nine children, it said.
Another person was wounded when an explosion occurred in front of Globa Park, and another explosion took place near the Opera, causing no injuries, according to the preliminary ministry's reports.
The injured were transported to local hospitals, and investigations were already under way, authorities said.
Criminal proceedings have been initiated over the blasts on charges of terrorism.
Following the blasts, Ukrainian President Viktor Yanukovych said the explosions were a challenge for the whole country.
"The best detectives will be involved to investigate the explosion," he said during his visit to Crimea peninsula in Ukraine's south.