There was some conflict in Mariupol with three Ukrainians ending up dead after protesters went to a military base. There are some videos but it is unclear what actually happened. There is a chance that provocateurs were involved.
The OSCE has an observer mission in Ukraine. From their latest (April 15) report:
The Lviv Team was told by Right Sector activists that they had begun recruiting for their paramilitary structure on 14 April. They said that approximately 100 paramilitaries had already been deployed to Donetsk region and were being trained in the eastern part of the country. One of the paramilitaries seen in Lviv was wearing a new military uniform, including a flak jacket, but carried no weapons.
There was a demonstration in Kyiv in support of Ukraine’s unity, attended by approximately 400people, about two thirds of whom were members of the Self-Defence force. The Team observed around 50 people armed with iron bars, baseball bats or makeshift clubs. Some protesters demanded the resignation of Interior Minister Avakov and more decisive action by the Kyiv authorities in Eastern Ukraine.
Lviv is in west Ukraine and the center of the Ukrainian fascists. That these deploy to Donetsk is a real concern that could lead to serious escalations.
(I am traveling and will have not much Internet time. Please behave in the comments and don’t feed the trolls.)