Ukraine’s army denied it carried out any shelling in the area at the time.
The region has seen a spike in violence in recent weeks, threatening a fragile ceasefire between the army and rebels.
A spokesman for the so-called Donetsk People’s Republic said 15 people were also wounded, as they crossed between rebel- and government-held territory.
At least four civilians – including a pregnant woman – have been killed in shelling at a checkpoint crossing in east Ukraine, pro-Russian rebels said.
