More than 20,000 people were evacuated in Balakliya, Ukraine on Thursday after an arms depot caught fire and sent rockets and debris flying over the city.
The base in Balakliya, near Kharkiv, is around 100km (60 miles) from fighting against Russian-backed separatists. The dump is used to store thousands of tonnes of ammunition including missiles and artillery weapons.
Rescue teams are overseeing a huge evacuation effort for people living in the city and nearby villages.
The total area of the dump spans more than 350 hectares, the military says.
Everyone within a 10km (6 miles) radius of the dump is being evacuated, the Interfax news agency quoted an aide to President Petro Poroshenko as saying.
Munitions from the depot are used to supply military units in the conflict zone in nearby Luhansk and Donetsk, reports say.
The authorities are investigating various ways the explosions may have been caused, Defence Minister Stepan Poltorak said, including the possibility of an explosive device being dropped from a drone.
Mr Poltorak said that there were no reports that civilians or serviceman had been killed or injured in the latest incident and that airspace had been closed within a 50km (31 miles) radius of Balakliya.
It’s an absolute miracle that no one was killed or seriously injured…