Government troops pressed on against separatists in the Donetsk area, near the Russian border, throughout last night, taking back a television broadcast tower in Kramatorsk, Interior Minister Arsen Avakov said on his Facebook account.

Open clashes are sweeping Ukraine’s east and south, from Donetsk to Odessa, about 100 miles from the European Union’s southeastern frontier in Romania, amid signs the industrial and coastal regions are slipping out of the Kiev government’s control. The easternmost region is “essentially at war,” the head of the country’s anti-terrorist agency said yesterday.

“We are not far from a civil war,” even if the government says it’s being driven by outside forces, Timothy Ash, an emerging-markets economist at Standard Bank Plc in London, said in an e-mail. “All told, little evidence of any de-escalation in the conflict in Ukraine and little evidence of any back-room efforts to broker a solution.”

The government’s operation in the Donetsk region left five dead and 12 wounded, Vasyl Krutov, head of Ukraine’s anti-terror agency, said yesterday. Government forces secured Slovyansk as operations in Kramatorsk continued, he said. International monitors who had been held by pro-Russian separatists were released yesterday, while Russia said it’s receiving calls for help from residents of the warring areas.

The assault in Slovyansk marked the biggest operation yet by the Ukrainian government to retake ground from as many as 1,000 armed gunmen who’ve seized buildings in more than 10 towns and taken several dozen captives.

In Odessa in the south, 42 people were killed and 125 injured in a building fire and street battle that began late May 2, when pro-Russians attacked marching football fans and a pro- Ukrainian rally.

On Sunday, hundreds of pro-Russian activists attacked a police station in Odessa, forcing open its gate and breaking windows and calling for the release of their detained comrades. Later in the day, police started to release the pro-Russian activists, a Reuters photographer said.

Catherine Ashton, the European Union’s foreign policy chief, urged an independent investigation of the incident and urged “everyone to exercise utmost restraint and not to exploit this tragedy to fuel more hatred, division and senseless violence,” according to a statement on her website.

Ukraine’s government, the U.S. and the EU accuse Russia of fomenting the unrest to undermine presidential elections scheduled for May 25.

“We, Ukrainians, are now constantly pushed into confrontation, into civil conflicts and to ruination of the country from inside,” acting President Oleksandr Turchynov said on his website yesterday. “We cannot allow this to happen and have to be united in our fight with a foreign enemy who wants to destroy Ukraine.”

Russian President Vladimir Putin is “extremely concerned” and is studying the situation, his spokesman Dmitry Peskov, said yesterday.

Peskov said Kremlin officials are getting “thousands of calls” from Ukraine seeking help. Putin has yet to decide how to respond to the escalating conflict, he said.

“People are calling in despair,” he said in a phone conference with reporters. “They are asking for help. The vast majority are asking for help from Russia.”

In a day of continued violence, in which the airport at Kramatorsk was wrested back from pro-Russian separatists, Organization for Security and Cooperation in Europe observers were freed yesterday in Slovyansk near Donetsk. The monitors had been taken hostage more than a week ago.

In other clashes , about 200 pro-Russian protesters, armed with batons and waving Russian flags, stormed and seized the security service’s vacant regional headquarters in Donetsk, according to Interfax. A group of armed activists took over a police building in Horlivka, according to Ukrainska Pravda.

Ukrainian Prime Minister Arseniy Yatsenyuk yesterday urged the security service to act more quickly to free three special- forces soldiers captured in Horlivka earlier.

A pro-unity rally in Kharkiv set for today was canceled after the violence in Odessa, organizers said on Facebook.

U.S. Secretary of State John Kerry said yesterday that he spoke to Russian Foreign Minister Sergei Lavrov by phone to tell him Russia must stop supporting separatists in Ukraine.

“It’s important for Russia to withdraw support from the separatists and to assist in removing people from the buildings and begin to deescalate the situation,” Kerry said in remarks to the press in Kinshasa, Democratic Republic of Congo.

In a website statement following the conversation, Lavrov said he warned Kerry about a “fratricidal conflict” brewing in Ukraine. He also urged the U.S. to get Ukraine to stop the offensive in the eastern regions.

U.S. intelligence officials have warned for at least a month of a possible Russian-orchestrated campaign in Odessa similar to those in Crimea and in Ukraine’s easternmost, largely Russian-speaking regions.

Not only does the port city have economic and military significance, it sits between Crimea and pro-Russian areas in eastern Ukraine and the breakaway Transnistria region of neighboring Moldova.

Russian citizens took part in provocations before the bloodshed in Odessa, the Ukrainian Foreign Ministry said in a statement on its website. Their aim was to destabilize the region, the ministry said, citing information from detained Russian citizens.

Some anti-Kiev protesters are demanding a referendum on joining Russia akin to the ballot that led to Russia’s annexation of Crimea from Ukraine in March.

Economic sanctions imposed on Russia by the U.S. and the EU have so far targeted officials, individuals and companies tied to Putin’s inner circle. The next step would be action against Russian industries, including banking and energy. Those penalties would have consequences mostly for European countries, which have more extensive economic ties with Russia than the U.S. does.

At a joint news conference on May 2 in Washington, U.S. President Barack Obama and German Chancellor Angela Merkel said Russia must pull back support for the separatists so Ukraine’s May 25 presidential election can proceed unimpeded.

If the vote can’t be held, “we will not have a choice but to move forward” with more sanctions, Obama said.