An explosion in the small hours of Thursday triggered a fire and a chain detonation of munitions at a military depot near the city of Balakleya in Ukraine’s Kharkov region, Ukrainian 24 TV reports.

"A powerful explosion occurred at a military base in Balakleya" at the biggest in Ukraine ammunition depot, the TV channel reports. According to local media, residents are evacuated.

According to eyewitnesses cited by 24 TV, streets are swarmed with cars leaving the city.

A short video shows a glow of major fire and new explosions are heard every second. There have been no immediate reports about casualties or damage.

Ukraine’s UNN (Ukrainian National News) news agency said the fire started at around 3.00 am local time (0100GMT). At the moment, a crisis center has been deployed in the area and measures are taken to localize the fire. A group of officers from the Defense Ministry led by Deputy Defense Minister Lieutenant General Igor Pavlovsky are heading to the site.

Sabotage was said to be the cause of explosions followed by fire at an ammunition depot in Balakliia, causing their detonation, the country's military prosecutor Anatolii Matios said.

"As a result of sabotage, an explosion occurred (fire broke out) at 03:02 am [01:02 GMT] at several rocket and artillery weapons storage sites (125 and 152 mm tank and artillery shells), which caused the detonation of ammunition," Matios wrote on his Facebook page.

Matios said regional authorities and law enforcement authorities have been dispatched to the scene, in addition to a commission from Kiev under the Ukrainian deputy defense minister for armaments' command.

"The total area of the arsenal is 368 hectares (909 acres) and 138,000 tonnes of ammunition," Sputnik cited him as saying.

Matios said an unmanned aerial vehicle is ready for deployment to establish the area of the damage.

The deputy director of the Political and Military Analysis Institute, Alexander Khramchikhin, speaking with a correspondent of Vestnik Kavkaza, noted that the loss of such a large arsenal will have a very bad impact on the combat capability of Ukraine's Armed Forces. "I do not know exactly how many thousands of tons of ammunition Ukraine has now, since it is almost impossible to keep track of, but the loss of such amount in any case is a very hard thing for the Ukrainian Army," he said.

The editor-in-chief of the newspaper 'Journalistic Truth', Vladislav Shurigin, in turn, drew attention to the fact that, despite the severity of the loss, Ukraine's Armed Forces will be able to fill it in due course. "We cannot say that it was fatal, there is more than one such depot in Ukraine, but it is a very serious loss, since voiced 138 thousand tons are the volumes used in a large front-line operation. For example, in the war of December 2014 - March 2015 a little less was used. But it will not put an end to the current events in Ukraine, and it's not just a large number of depots left from the Soviet era, but also in the production of ammunition," Vladislav Shurygin said.