MARIUPOL, Ukraine - Gunfire and heavy shelling rocked a key frontline city in eastern Ukraine overnight, raising fears Sunday that a tenuous truce between government and rebel forces had already collapsed.
Artillery fire was also heard Sunday near the airport of the main rebel-held city of Donetsk, AFP correspondents said.
Pro-Russian fighters had bombarded a government-held checkpoint on the eastern edge of the strategic port of Mariupol late Saturday, triggering a firefight that sent local residents into panic.
"Everyone is starting to flee," one 46-year-old Mariupol resident who gave her name only as Victoria told AFP.
"I'm frightened. I want peace but I think this ceasefire is finished, this is the third night we haven't been able to sleep." The violence erupted just hours after a phone call between Ukraine's President Petro Poroshenko and his Russian counterpart Vladimir Putin, who agreed that the ceasefire was "generally being observed".
The 12-point pact signed Friday was the first to gain the backing of both Kiev and Moscow after five months of fighting that set off the deepest crisis in East-West relations for a generation.
It was drawn up after the rebels - reportedly backed by large numbers of Russian troops and firepower - launched a lightning counter-offensive across the southeast in late August that dramatically reversed recent gains by the Ukrainian army.
Mariupol became the latest flashpoint when the insurgents pushed southwards in what is seen as a drive to carve out a land corridor between the Russian border and the strategic Crimean peninsula annexed by Russia in March.
The situation was calm early Sunday but a truck was ablaze on a road near the checkpoint, and several buildings were damaged, according to AFP correspondents in the Azov Sea city.
The violence threatens a repeat of the unilateral ceasefire called by Kiev in June, which collapsed within days.
"You see what type of ceasefire there is on the Russian side," said a fighter with a pro-Kiev volunteer battalion in Mariupol. "Who knows what's going to happen today."