Fire Station No. 2 on Bloomfield Avenue subsequently closed and is forced to rely on mutual aid from neighboring towns and Fire Station No. 1 because of the event, Township Manager Matthew Cavallo said.
It was not clear when the party happened or how many firefighters were exposed.
"The holiday gathering was not authorized by the Township and actions have been taken to ensure similar incidents will not happen in the future," Cavallo said.
Local officials were working on a plan to help the fire department return to full service.
"With these deliberate steps, residents and businesses will remain safe and protected," Cavallo said.
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