Alexei Murzhankov, a duty officer at the Vitebsk city department of the ministry, said 25 of those injured in last night's blast were hospitalized, four of whom were in intensive care.
Murzhankov said the explosion occurred just outside the Eridan cafe, a temporary, partially open-air structure of the sort often set up to attract customers in the summer. The cafe has a dance floor and an outdoor area.
The bomb, which had been packed with pieces of metal, had been buried in a flower-bed outside the cafe, the Vitebsk regional police said. The composition of the device, and the fact that the explosion occurred when the square was crowded with customers, accounts for the large number of injured but apparently minimal damage to the cafe tent itself, which was shown intact on television.
Investigators did not discuss possible motives for the attack, but the location suggests a business dispute could not be ruled out as a cause. The Belarusian Security Council said it was looking at several scenarios, including a fight between criminal gangs and hooliganism, the RIA-Novosti news agency reported.It was the second such explosion in the town, 300 kilometres northeast of the capital, Minsk, in just over a week.
In the previous incident on 14 September, a homemade bomb - a beer can stuffed with nails and metal scraps - was planted in a flower-bed near a bus stop close to a theatre. That blast wounded two people.
Prosecutors launched an investigation on charges of hooliganism in last week's incident.
Vitebsk is best known outside Belarus as the birthplace of painter Marc Chagall.