According to the report, the militants fired twice in the direction of residential areas.
In addition, the militants fired 120mm mortars along the demarcation line, in what the Ukrainian military said was a gross violation of the Minsk agreements.
"In the area of the village of Pisky, the militants fired 120mm mortars twice at a fortified position of the Ukrainian armed forces," the report says.
"At about 2300, in the area of Mariupol the militants fired 120mm mortars at our fortified position near the village of Talakivka. They also fired automatic grenade launchers and machine guns near the towns of Avdiivka and Popasna, and the village of Opytne," the report reads.
In Luhansk region, the militants fired mortars on the positions of the Ukrainian army near the village of Syze in Stanychno-Luhansk district.
"Russian-backed militants have increased their attacks on residential areas. From 2100 to 2150 they fired machine guns and 120mm mortars twice on the village of Pisky," the headquarters said.
"As reported, on April 16 the militants fired 120mm mortars on the town of Avdiivka," the report says.
"During this period, the Ukrainian army recorded five reconnaissance overflights by enemy drones in Luhansk region and near Mariupol. One of them, flying near the village of Butkivka of the Starobilsk district, was shot down by a Ukrainian anti-aircraft missile system," the headquarters said.