KHARKIV, Ukraine –- Against the backdrop of an escalating crisis that threatens to tear Ukraine apart, thousands turned out for May Day on Thursday in this city 20 miles from the Russian border.

In typical fashion, Communist Party members and pro-Russia groups paraded down main drags waving hammer-and-sickle flags of decades past while marching to traditional Soviet labor tunes.

The group was smaller than in previous years, with a mere 1,000 or so gathering in Kharkiv's central Freedom Square. Rally-goers carried portraits of Soviet leaders Vladimir Lenin and Josef Stalin, and at least one — taking a page from Paul McCartney’s songbook — donned a sign that read: “Back to the USSR.”

May Day parade in #Kharkiv underway, with plenty of Stalin, Lenin, USSR flags, chants of "Russia!" and "Referendum!" pic.twitter.com/dDNmcaOkGI — Christopher Miller (@ChristopherJM) May 1, 2014



More than 2,000 May Day demonstrators turned out in nearby Donetsk.

The event there turned violent when hundreds of participants split off from the main rally and clashed with police outside the Regional General Prosecutor’s office. Protesters said they’d come in peace, demanding to speak with the prosecutor general.

But the crowd went on the offensive when he failed to appear. Police in riot gear hurled tear gas and flash grenades into the pro-Russian mob, which used sticks and fists against the officers. Rubber bullets were reportedly fired by police from the windows of the building into the violent crowd. Some protesters were photographed with handguns believed to be air-powered. Several injuries were reported.

Violence erupts outside Prosecutor's building in #Donetsk. Pro-Russia activists attack police lines: tear gas, stun grenades, rocks thrown — Steve Rosenberg (@BBCSteveR) May 1, 2014



Back in Kharkiv, the threat of violence loomed large, with hundreds of people breaking away from the main rally on Freedom Square to shout down police officers dressed in riot gear in front of the Regional State Administration building.

Horns and victory songs blaring now at #Kharkiv govt building. pic.twitter.com/9ChsbaHPDH — Christopher Miller (@ChristopherJM) May 1, 2014



Entire #Kharkiv govt bldg guarded by police. Still, outnumbered by pro-Russian crowd here. pic.twitter.com/KmDLPtD3Gh — Christopher Miller (@ChristopherJM) May 1, 2014



Several journalists were forcibly removed and threatened by the pro-Russian crowd, though they weren't injured. Pro-Russian protesters had previously stormed the building in April, breaking several windows and tossing Molotov cocktails inside. Police later recaptured the building. Shards of shattered glass remained inside the window frames, however, which have since been boarded up.

Tensions subsided hours after the event had begun, as the crowd scattered in all directions, discarding many of their flags and signs on the streets and in trashcans around the city's square.