An attack on a Ukrainian national guard base turns bloody.br br Three people were killed in the eastern city of Mariupol, making it the bloodiest day in the region's 10-day uprising.br br There a group of masked men tried to take over a military unit.br br One masked man said they had called on Ukrainian forces for peaceful talks.br br (SOUNDBITE) (Russian) ANOTHER UNIDENTIFIED MASKED MAN, SAYING:br br "You need to understand the most important thing - they not only refused to talk to us, the soldiers didn't even spare a word. They first stood across the area and nobody would talk to us. We had a feeling that these people weren't Mariupol residents. We called on them empty-handed for talks, asked them to pass it (the request) over to their boss, we said we didn't want to shoot, not a single shot. But they would shoot into the air."br br In the morning, investigators gathered evidence of the bloodshed.br br Bullet casings sat empty near a gray Ukrainian police vehicle.