Russia-backed separatist representatives in eastern Ukraine say at least five people were killed in an attack on a checkpoint in the town of Olenivka.
Eduard Basurin, who represents Russia-backed separatists' armed forces in parts of the Donetsk region, said on April 26 that 10 more civilians were injured by artillery fire from the Ukrainian side.
The people had apparently been waiting several hours in a queue to pass into territory controlled by Ukrainian government forces.
Kyiv has denied the separatists' accusations of opening fire on the checkpoint.
A local border-guard spokesman, Anatoliy Kotsurba, was quoted as saying there was an explosion at the checkpoint but he saw no artillery fired from either side, suggesting the blast could have been caused by a bomb.
Fighting between Russia-backed separatists and Ukrainian government forces has been raging for two years, claiming more than 9,100 lives.
The hostilities left some parts of Ukraine's eastern regions of Luhansk and Donetsk under the separatists' control.