Some 20,000 people are being evacuated after a series of explosions at a massive arms depot in eastern Ukraine described by officials as sabotage.<br/><br/>The base in Balakliya, near Kharkiv, is around 100 kms from fighting against Russian-backed separatists. The dump is used to store thousands of tonnes of ammunition including missiles and artillery weapons.<br/><br/>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.