Local health officials said an anti-personnel mine detonated while several employees worked to defuse it.
Local emergency services spokesman Octavian Fulger said four of the injured were in stable condition.
An investigation into the incident has begun, Fulger said.
The Babene facility is part of the Energotech group, produces weapons and ammunition, and is a supplier to the Romanian and NATO Defense Ministry.
In 2019, there was an explosion at the plant, which killed a 22-year-old worker.
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