“We were lucky the explosion didn’t take place in the production halls,” Cacak Mayor Milun Todorovic told state broadcaster RTS television.
Officials said firefighters would be able to go into the factory to assess the situation 24 hours after the last explosion. They said later Friday they expected the fire to be fully extinguished by next week and the factory to back in operation on Monday.
RTS reported that most evacuated residents had returned to their homes by midday.
Serbian President Aleksandar Vucic told reporters that early damage estimates reached up to 2 million euros ($2.4 million).
Sloboda is the biggest munitions factory in Serbia. It was targeted in a 1999 NATO bombing campaign during the war in Kosovo.