A powerful explosion occurred at a military plant in the rebel-held Ukrainian city of Donetsk after a shell hit it. A fire is now ravaging the damaged facility.

The plant was used for producing explosives and ammunition as well as for dismantling unexploded munitions collected on the battlefields. On Saturday morning, residents of the war-torn city heard a powerful blast, which was followed by a huge cloud of white smoke rising into the sky.

A neighborhood official told Ukrainian 112 television that a shell hit the plant.

“There was a direct hit at the No 47 industrial explosives shop, where some explosives were present. It detonated and caused another explosion. Luckily it didn’t hit the main storage facility where we have some 2.5 tons of explosives,” said Ivan Prikhod’ko, deputy chair of the local community council.

He added that while the incident caused considerable damage, nobody was hurt. The plant itself was not working at the time, so no one was there. Also, it was built far from any residential areas specifically for safety purposes.

As the fire continued, smaller explosions could be heard, presumably from shells detonating in the fire, RIA Novosti reported.

There is no verified report about what kind of weapon hit the plant. But there are rumors of it being targeted by a Tochka-U tactical missile launched by Kiev's troops.

“According to our information, three Tochka-U missiles were fired and there you have it,” a militia member who identified himself as codename ‘Scorpio’ told RT. He added that the area around the plant was considered dangerous lately because both the rebels and their opponents could shell it.

Donetsk saw sporadic shelling overnight.

The incident mars Friday’s signing of an extended ceasefire deal between Kiev and rebel forces, which hopes to put an end to hostilities in eastern Ukraine. The deal includes pulling back all heavy weapons from cities and frontlines.

The blast happened just as a Russian humanitarian aid convoy was unloading elsewhere in the city. Some 200 trucks carrying 2,000 tons of aid crossed the border earlier on Saturday.