Petr David Josek, Associated Press
An injured Ukrainian soldier Vadim Pugovetsa sits in his room at a hospital in town of Artemivsk, Ukraine, Thursday, Jan. 29, 2015. Fighting between government and Russian-backed separatist forces in eastern Ukraine has intensified in recent days as rebels seek to encircle the town of Debaltseve, which hosts a strategically important railway hub.

KIEV, Ukraine — Artillery fire in the rebel stronghold of Donetsk has killed at least 12 civilians as the fighting between pro-Russia separatists and government troops intensifies.

Donetsk city hall says five people were killed early Friday afternoon as they were waiting for humanitarian aid outside a community center and two people were killed when a mortar shell landed near a bust stop. Five other people died Friday in sporadic artillery fire in the west of Donetsk.

Full-blown fighting between the rebels and government forces erupted anew earlier this month following a period of relative tranquility. Hostilities now seem to be focused around Debaltseve, a railway hub which could prove a crucial link between the rebels in Donetsk and in Luhansk northeast to it.