Russian-speaking regions of Ukraine spun further out of the central government’s control Sunday as a mob stormed a police station in this Black Sea port and freed from detention 67 pro-Russian militants, on the same day that Ukraine’s prime minister was visiting the city.

It was intended to be a chance for the prime minister, Arseniy P. Yatsenyuk, to express condolences for the dozens of people who died here Friday in street fighting and in a horrific fire at a trade union building, and to reinforce the government’s narrative that Russia and inept or disloyal local police were to blame.

Speaking at a news conference, Mr. Yatsenyuk cast aspersion on the police, suggesting that if they had done their jobs instead of concentrating on soliciting bribes at an outdoor market, “these terrorist organizations would have been foiled.”

“There were dozens of casualties resulting from a well-prepared and organized action against people, against Ukraine and against Odessa,” Mr. Yatsenyuk said, speaking at the news conference Sunday morning, Western and Ukrainian news media reported.

He denounced Russia’s claim that Ukraine was not seeking a compromise with its Russian-speakers. “The process of dialogue had begun, only it was drowned out by the sound of shooting from automatic rifles of Russian production,” he said.

Mr. Yatsenyuk said the violence showed that Russia wanted to kindle unrest in Odessa, as it had in eastern Ukrainian cities. Odessa is a major port between the Crimean peninsula, annexed by Russia in March, and the Russian-backed separatist enclave of Transnistria in Moldova on Ukraine’s eastern border.

Russian President Vladimir Putin, in a speech last month, hinted at a claim to an entire arc of Russian-speaking regions in the east and the south of Ukraine by calling these provinces of steppe and Black Sea coastline “Novorossiya,” or New Russia, as they were known after Catherine the Great’s conquest of the region in the 18th century. Russia has said it does not intend to invade, though tens of thousands of its troops are still positioned on the border.

The violence Friday and the freeing of prisoners Sunday highlighted a distinction between Odessa and the east: In both places, the police have sided with rebels. But here, local pro-Kiev activists routinely field street fighters ready to confront the Novorossiya group, with lethal consequences on Friday.

At the police station Sunday, the riot police stood idly by as men and women gathered, banging on a gate and chanting – and then demonstratively walked through the crowd led by a uniformed man wearing the black-and-orange ribbon that is a symbol of pro-Russian groups.

Soon enough, the prisoners emerged through the gate, pumping their fists in the air to chants of “heroes! heroes!”

The men belong to a group known as the Activists of Kulikovo Field, which had camped out on the square of that name in Odessa. They had been in jail for two days after being rescued from the trade union building blaze that killed at least 40 other pro-Russian militants.

After establishing a tent camp on Kulikovo Square, the activists, following the example of pro-Russian groups in Donetsk in eastern Ukraine, had proclaimed an independent state, the Republic of Novorossiya. An exile in Moscow then claimed the presidency.

But unlike in eastern Ukraine, they faced strong opposition from pro-Ukrainian activists, including soccer fans. The fan clubs of the Chernomorets and Metalist teams, who had a long and fierce rivalry that often led to fights, recently declared a truce because of the crisis. Before a match on Friday, they scheduled a march in support of Ukrainian unity down Deribasovskaya Street, a pedestrian thoroughfare in the heart of the city.

The fighting started when the Activists of Kulikovo Field tried to block the march. Leaflets went up around Odessa on Friday morning, announcing the pro-Russian action to “defend Odessa from pogroms,” and the city braced for violence.

What followed were hours of bloody street clashes involving bats, pistols and firebombs. Many in the pro-Russian group carried bowie knives, photographs show. Four people died on and around Deribasovskaya Street. The pro-Russians, outnumbered by the Ukrainians, fell back, abandoning their tent camp on Kulikovo Square, which was burned by their opponents. Many then sought refuge in the trade union building.

Yanus Milteynus, a 42-year-old construction worker and pro-Russian activist, said he watched from the roof as the pro-Ukrainian crowd threw firebombs into the building’s lower windows, while those inside feared being beaten to death by the crowd if they tried to flee.

“Some people jumped or tried to run away, but they chased them, and beat them,” he said. Videos of the inferno, however, also show pro-Ukrainian activists trying to move scaffolding from a stage to the building, to rescue those inside.

Only when the police managed to form a cordon to escort out those rescued by firefighters was he able to leave. If the roof caught fire before then, he said, “I would have stayed and sizzled like a sausage in a frying pan.”

The U.S. ambassador to Ukraine, Geoffrey R. Pyatt, in a telephone interview with CNN, called for an investigation into the violence here and suggested that local police were complicit.

Even against the incessant backdrop of violence in the Ukraine crisis, the causes of the fire at the trade union building and its terrible toll in lives is sure to be carefully parsed. The Russian foreign ministry has cited the blaze as justification for pro-Russian groups to take up arms.

ODESSA, UKRAINE — The New York Times News Service
Published Sunday, May. 04 2014, 8:27 PM EDT
Last updated Sunday, May. 04 2014, 8:37 PM EDT