By Pavel Polityuk and Natalia Zinets
LVIV, Ukraine (Reuters) -Ukrainian civilians and foreign students clutching bags and rucksacks fled the besieged city of Sumy in buses and cars on Tuesday in the first successful "humanitarian corridor" opened since Russia's invasion.
Ukraine accused Russian forces of shelling one evacuation route - from Mariupol in southern Ukraine - but Sumy's regional governor said a temporary ceasefire had held long enough for at least two convoys of vehicles to leave the northeastern city.
The first evacuation convoy met a column of more than 160 Russian military vehicles coming towards them on the road, said Sumy Governor Dmytro Zhyvytsky in televised comments.
"Our column stopped on the side of the road and let the vehicles through, then continued on its path," he said.
People stood patiently on the snowy ground in Sumy, waiting for the evacuation buses. Many had packed as many belongings as they could into a single bag, and some had their children with them. All were wrapped in warm winter clothes.
Around 1,000 foreign students were among the first wave of evacuees, Zhyvytsky said.
Some civilians were also evacuated from the town of Irpin near the capital Kyiv. There were no reports of them coming under fire in Irpin, two days after Reuters witnesses said residents trying to flee were caught in Russian shelling.
But foreign ministry spokesperson Oleg Nikolenko said the evacuation route from Mariupol had been shelled and local officials said people had been unable to leave the city, which has been under fire without water or power for over a week.
"Ceasefire violated!" Nikolenko wrote on Twitter (NYSE:TWTR). "Pressure on Russia MUST step up to make it uphold its commitments."
There were no immediate reports of any casualties and Nikolenko gave no other details. Russia did not immediately comment on his remarks.
Civilians have been trapped by fighting since Russian troops invaded Ukraine on Feb. 24. Humanitarian corridors from Mariupol failed on Saturday and Sunday, with each side accusing the other of continuing to fire.
Ukraine refused to use any humanitarian corridors offered by Russia that would have taken Ukrainians into Russian or Belarusian territory.
Ukrainian officials say food, water and other supplies have been running low in some of the besieged cities, and some have warned of a "humanitarian catastrophe".
Moscow calls its actions in Ukraine a "special military operation" to disarm its neighbour and denies targeting civilians.