( CNN ) -- Four explosions that rocked an eastern Ukrainian city on Friday have prompted a terror probe , the Ukrainian News agency reported . A regional prosecutor 's office has started a `` terrorist case '' into the blasts in Dnepropetrovsk . The explosions went off in the course of 70 minutes and injured at least 27 . Ukraine President Viktor Yanukovych said a special investigation team will be set up to probe the explosions , the news agency reported . `` This is another challenge to the entire country , '' the president told reporters in the country 's Crimea region . `` We are thinking how to respond it properly . I am sorry this happened . '' The first blast went off in a trash can at a tram stop , injuring 13 people , the country 's Emergencies Ministry said . The second followed 40 minutes later near a movie theater . That injured 11 , nine of them children . Three were injured in the third blast , and no one was hurt in the fourth , the ministry said . Of those hurt , 24 have been hospitalized , it said . Interior Minister Vitaliy Zakharchenko and other government officials traveled to the city after the blasts occurred . The city , with just over 1 million in population , is one of the largest in the country , the CIA World Factbook says . The incident raises concerns about security in Ukraine ahead of the European soccer championships , starting in June in both Poland and Ukraine . But the Union of European Football Associations , the entity overseeing the games , said the incident does n't change its `` confidence in the security measures that have been developed by the authorities . '' The closest venue to Dnepropetrovsk will be in a Ukrainian city to the east , Donetsk .
NEW : The incident raises concerns in advance of the European soccer championships . Four blasts are reported in Dnepropetrovsk in eastern Ukraine . Ukraine opens a terror case into the blasts .