The main airport in Ukraine's eastern city of Donetsk was rocked by an explosion and heavy shooting on Monday after armed rebels seized the facility, an AFP correspondent at the scene said.
Thick black smoke was seen rising from the airport complex as the sound of heavy machinegun fire rang out and fighter jets could be heard overhead.
Scores of armed separatists had earlier seized control of the modern airport, which was revamped for the 2012 European football championship, halting all flights out of the rebellion hit city.
The strategic transport hub had been evacuated and sealed off after gunmen claiming to be from the self-declared "Donetsk People's Republic" showed up overnight demanding that Ukrainian troops guarding the airport perimeter be withdrawn.
The raid was launched in the hours after billionaire Petro Poroshenko claimed victory in a presidential election Sunday that the pro-Russian rebels have dismissed as illegitimate.
"At 3:00 in the morning, a group of armed men came. There was no shooting," airport spokesman Dmytro Kosinov told AFP.
The last scheduled airplane allowed to leave was the 7:00 am (0400 GMT) flight to Kiev.
"We do not know when we will be up working again," Kosinov said.
An AFP journalist saw three military trucks with scores of well-armed men in camouflage, some wearing pro-Russian ribbons and others with Cossack hats and beards, driving towards the airport through a traffic police checkpoint a few hundred metres from the main terminal.
Airport officials stopped media and passengers wanting to travel from getting close enough to the main entrance to see the airport buildings but an AFP journalist saw people walking around on the roof of the modern terminal from another location on the edge of the airport territory.
It was too far away to see if the people were armed.
Separatists in the heavily-Russified eastern rust belt of the ex-Soviet nation launched an insurgency against Kiev's rule in early April and have seized about a dozen cities and towns in the Donetsk and Lugansk regions neighbouring Russia.
- 'Not our president' -
The rebels thwarted voting across parts of eastern Ukraine during Sunday's presidential election and several commanders said they did not recognise Poroshenko's legitimacy and would continue their independence fight.
"We consider that the winner of the election is president of west Ukraine -- he is a half president," said Oleh Tsarov, a former member of the Regions Party of toppled pro-Russian president Viktor Yanukovych.
The armed rebellion blocked voting across most of Donetsk and Lugansk, two regions that together make up around 15 percent of the national electorate.
Poroshenko has pledged to try to bring peace to Ukraine but said Monday he would press on with a military offensive against the "terrorists" in the east.
"Let the people who elected him recognise him but for us here he won't be our president," said pro-Russian shopkeeper Tetyana Krasikova.
"In the east his election won't change anything," she said. "The people have been too humiliated, too many have died to go back to the way things were."
Others in Donetsk threw their support behind the likely new president despite not being able to vote.
"For me it is a positive step -- and not only because I like his chocolate," said small business owner Anton Berdshadsky, 32.
"Obviously his first challenge will be to solve the situation in the east but what can he do when the army doesn't work and war is already here? It will be difficult to change the way people think."