An explosion rocked a bus in the town of Debaltseve not controlled by the Ukrainian authorities at 3.30 p.m. 22 May, the separatist Donetsk News Agency has reported.
Bus No 1 was moving along Kurchatov Street.
"According to preliminary reports, the explosive was inside the bus. At the moment, we know that one person was killed and two were wounded," it said.
People in the local public community Debaltsevo DNR are saying that children in the rear of the bus were playing with a grenade when it went off.
Russian TV journalist Aleksandr Slakov said on Telegram that the grenade fell out of a teenager's pocket and exploded.
The self-proclaimed Donetsk People's Republic captured Debaltseve in February 2015 although under the Minsk agreements the city must be under control of the Ukrainian authorities.