Dozens of pro-Russia activists have been freed from police detention in Ukraine's southern port of Odesa after a crowd of some 2,000 surrounded police headquarters demanding their release.
The pro-Russian crowd forced a gate and broke windows at the police station on May 4.
Ukraine's Interior Ministry said in a statement the same day that 67 pro-Russian activists were released. It was not immediately clear whether others were still being held.
The activists had been detained after a fire and fighting in the southern Ukrainian port city that left more than 40 people dead on May 2.
Most of the victims died in a blaze apparently started by firebombs thrown inside the building where pro-Russia activists had sought refuge amid the street fighting with pro-Ukraine demonstrators.
Ukrainian Prime Minister Arseniy Yatsenyuk visited Odesa on May 4 and accused Russia of engineering the violence.
Speaking in the Black Sea city, Yatsenyuk, said the "destruction of the country and splitting of the country -- this is the Russian plan."
Yatsenyuk also blamed security forces for failing to prevent the violence and promised a full investigation.
Meanwhile, Interior Minister Arsen Avakov said an "antiterrorist operation" was continuing in several towns under the control of pro-Russian forces in the mainly Russian-speaking eastern Ukraine.
However, there were no signs on May 4 of Ukrainian troops pushing to remove separatists from eastern cities, including Kramatorsk, Donetsk and the rebel stronghold of Slovyansk.
Kyiv announced an "antiterrorist" operation in the region on April 15, but it appears to have been limited in its effectiveness.
Meanwhile, German Foreign Minister Frank-Walter Steinmeier has called for a second international conference to put an end to the Ukrainian crisis.
Steinmeier said he made the proposal in telephone conversations on May 4 with EU foreign policy chief Catherine Ashton, U.S. Secretary of State John Kerry, Russian Foreign Minister Sergei Lavrov and the Organization for Security and Cooperation in Europe (OSCE).
On April 17, the United States, Russia, Ukraine and the European Union signed an agreement in Geneva that outlined steps to defuse the crisis.
The deal included the disarmament of militants and a national dialogue on constitutional reform.
The OSCE is charged with overseeing implementation of the accord.
Russia and Ukraine accuse each other of undermining the Geneva deal.
In Moscow, Russian Deputy Foreign Minister Grigory Karasin said on May 4 that the events in Odesa showed that the Ukrainian authorities were unable to establish a dialogue with the pro-Russia population in the east of the country.
Karasin said the tragedy in Odesa should serve as "a warning for the entire world."
With reporting by Reuters, AFP, ITV, and Interfax