The West Orange Police Department says the series of events began after 3 p.m. at the Krauszer's convenience store at 12 South Valley Road in West Orange.
They say an off-duty West Orange Police officer suffered a non-life-threatening injury during an attempt to intervene in a robbery at the store.
The suspect fired once before fleeing.
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The officer was taken to University Hospital in Newark, where he is in stable condition and being treated.
Police say a potential suspect is in custody and a vehicle was been detained by Newark Police at an Exxon gas station at South Orange Avenue and Bergen Street in Newark.
Authorities say the injured officer may be able to make an identification of the suspect in custody.
The Essex County Prosecutor's Office is investigating.
This is breaking news. This story will be updated as more information becomes available.
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