DONETSK, Ukraine — Using fighter jets, helicopters, and artillery, Ukrainian forces battled to rid the airport of separatist fighters who seized it in the aftermath of national elections that seemed to marginalize them.
Fighter jets screamed and automatic gunfire popped as Ukrainian soldiers fought a ground battle around the airport against the separatists, who have taken over two eastern Ukrainian provinces.
After fighting that lasted into a rainy evening, the military appeared to have evicted the separatists from the airport, cordoning off the area with roadblocks. The airport remained closed.
Hundreds of rebel fighters were brought in trucks to an area at the edge of airport, many of them carrying automatic rifles and rocket-propelled grenade launchers.
The fighting began shortly after 1 p.m., when gunfire tore through a grassy area in front of the airport near a Toyota dealership. Thick black smoke dotted the sky.
A spokesman for the military said the operation was intended to “clear the territory.”
In other violence, Donetsk news agencies said two people were injured and one person killed by gunfire at the city’s main train station, the Associated Press reported. In Slovyansk, a city about 60 miles to the north, at least two people apparently were killed by government mortar fire, the AP said.
The fighting started a day after Petro O. Poroshenko, a Ukrainian billionaire, was elected president in a landslide. Poroshenko has pledged to calm the separatist violence in the east, which, despite Sunday’s election success, still represents a resilient threat to the country’s stability.
The military had been conducting an offensive to rid the areas of separatists but had suffered more setbacks than victories. Residents have expressed disdain over the military’s ineffectiveness.
The seizure of the airport suggested a new, perhaps desperate, escalation by the militants, who in recent days have appeared to lose the political support of the Kremlin, which indicated that it would respect the results of Sunday’s election.
The militants are unlikely to survive long without the backing of Russia. But support can come in many ways, and it is far from clear that President Vladimir Putin of Russia intends to give up what appears to be a useful geopolitical lever: violence and instability in Ukraine’s east that has left the West flustered.
Still, rebels seemed shaken by their isolation. At the Donetsk government headquarters that they have occupied and fortified with barbed wire and old tires, nervous separatists briefed journalists.
Denis Pushilin, the speaker of the self-proclaimed Donetsk People’s Republic, said that the rebel troops posted Sunday night to guard the building against attack had been fired upon by government forces.
“We must defend ourselves,” Pushilin said. “This is an important attack against a strategically important building.”
He said he did not expect an immediate attack on the headquarters but called on Putin directly for help.
“I am forced to appeal directly to Vladimir Vladimirovich Putin for any possible aid,” he said. When asked what kind of aid — military or economic — he said “any.”
Poroshenko’s election by a wide margin sent a clear message that Ukraine was prepared to move forward as a united, if besieged, country, with no indication of military action by Russia or any prospect of secession and annexation as occurred with Crimea.
Militants prevented voting throughout much of the east Sunday, prompting accusations from some observers, including a US senator, Kelly Ayotte, a Republican from New Hampshire, that Russia had failed to honor a demand that it not interfere with the balloting.
In Moscow, Sergey V. Lavrov, the foreign minister, said that Russia saw the vote in Ukraine as a positive step, albeit with problems.
“The fact that the elections were organized in most of the regions in Ukraine is generally positive,” Lavrov said at a news conference, echoing remarks by Putin that Russia would respect the outcome.