BELGRADE, Serbia (AP) — An explosion rocked a munitions factory central Serbia on Saturday in the second such incident this month, injuring at least three workers, state-run Serbian television reported.

A powerful explosion was heard just before 8 p.m. (1800GMT), followed by several smaller blasts, the TV report said. It added that the workers were slightly injured and treated at a local hospital.

Authorities have ordered an evacuation from the area around the Sloboda factory in Cacak, which remained sealed off, RTS said.

Reports from the scene showed thick mushroom-shaped smoke rising from the direction of the Sloboda factory as media said the detonation was felt throughout the area.

There was no immediate official statement about the incident. The previous blasts at a munition depot on June 4 forced evacuations around the factory but caused no injuries.

Sloboda is the biggest munitions factory in Serbia. It was targeted in a 1999 NATO bombing campaign during the war in Kosovo.