Hundreds of people have been killed in eastern Ukraine since a cease-fire was signed Sept. 5, bringing the overall death toll since the start of the six-month-old conflict to more than 3,500, the United Nations reported Wednesday.

The U.N. said no large-scale offensives have taken place since the cease-fire was announced, but that artillery, tank and small arms’ fire continues to be exchanged almost every day, while the humanitarian situation is grim.

Continued violence between Ukrainian forces and pro-Russian separatists is concentrated around the airport in Donetsk and the towns of Debaltseve and Schastiye, though Russian and Ukrainian officials said Tuesday there was further progress on the truce.

Since the cease-fire began, at least 331 fatalities were recorded, the U.N. said. It cautioned that some of the deaths may have occurred before the start of the cease-fire but were recorded later.

At least 3,660 people have been killed since the start of the conflict in mid-April, the U.N. said. A further 8,756 have been wounded.