A fire at a Russian ammunition depot has caused shells to explode and injured 30 people.

Authorities ordered the evacuation of more than 28,000 residents who live near the plant. They said Friday the blasts may continue for another day at the arsenal in the republic of Udmurtia, 900 kilometers east of Moscow. Balls of fire spiraled from the depot in repeated explosions and a thick column of smoke poured from the site. The blasts broke windows in buildings as far as 10 kilometers away.

Nine of the injured were hospitalized, some with burns. Authorities evacuated nearby towns, sending residents on buses to other locations as far as 60 kilometers away.

Russian television reported the depot housed old ammunition that was due to be decommissioned.

The cause of the fire was not immediately known.