DONETSK, Ukraine — Pro-Russian militants attacked police stations and other security facilities in the most populous part of eastern Ukraine on Saturday, in a brush fire of violent unrest that the government in Kiev immediately denounced as Russian “aggression.”

The attacks on the Police Headquarters here and on a police station and a state security branch in Slovyansk about 60 miles away, along with reports of shooting in several other towns, suggested a coordinated campaign to destabilize the Donetsk region, a vitally important industrial and coal-mining area that borders Russia.

A local journalist on the scene said the raid on the police station appeared to be the work of local pro-Russian militants rather than a repeat of the scenario in Crimea, where heavily armed Russian soldiers without markings on their uniforms seized control of airports and other vital installations in late February at the start of a Kremlin-orchestrated campaign to annex the region.