The judge said that the injured persons had been transferred to hospital. He added that two cars parked outside the building had been damaged by the blast.
The explosion was preceded by an argument involving several persons who were sitting on the terrace outside the offices of the local branch of the Croatian Party of Rights (HSP) in the building. At one point one of them walked away and soon afterwards there was an explosion, Besenski said.
Speaking at a press conference, the judge declined to answer a question if the explosion was preceded by an inter-ethnic conflict.
Asked if it was true that the police had sealed off the border with Serbia, police spokesman Miroslav Janic said that the Vukovar Police Department had stepped up control measures in the entire area under its jurisdiction.
An on-site investigation was in progress.