A series of explosions rocked a munitions factory in central Serbia early Friday, forcing the evacuation of workers and residents nearby and causing panic but no injuries.

Explosions at an ammunition depot at the Sloboda factory in Cacak, about 140 kilometers south of Belgrade, sparked a huge blaze that lit up the night sky above the city.

Police cordoned off the area, blocked roads leading to Cacak, and displaced people living near the factory from their homes. Workers at the factory hid in the basement when the explosions started.

The cause of the incident was not immediately clear. Serbian media reported that sporadic detonations could still be heard in the morning hours after starting around 1.30am.

“We were lucky that the explosion did not take place in the production rooms,” Cacak mayor Milun Todorovic told state broadcaster RTS.

Officials said firefighters could visit the plant to assess the situation 24 hours after the last explosion. They said later on Friday that they expected the blaze to be completely extinguished by next week and the plant to resume operations on Monday.

RTS reported that most of the evacuated residents had returned home by noon.

Serbian President Aleksandar Vucic told reporters early damage estimates were up to 2 million euros ($ 2.4 million).

Sloboda is the largest munitions factory in Serbia. He was targeted during a NATO bombing campaign in 1999 during the Kosovo War.

Belgrade, Serbia, The Associated Press