Pro-Russian protesters stormed the prosecutor's office in the separatist-held city of Donetsk on May 1, hurling rocks, firecrackers and teargas at riot police defending officials the rebels accused of working for Kyiv's Western-backed leaders. To shouts of "Fascists", a refrain Moscow uses to describe Ukraine's new government, hundreds of people pelted the police with paving stones and then cornered some, dragging them to the ground and beating them. The police soon surrendered.
Reuters: Pro-Russian protesters storm prosecutor’s office in Ukraine’s Donetsk

Regional Prosecutor's office seized by separatists in Donetsk on May 1.