"Apparently some guy was going around the store saying he voted for Trump and wanted to kill people who spoke out against [the President]," a law enforcement source said. "That got turned into [Facebook posts]."
The supermarket was initially evacuated and a Bergen County Regional SWAT team summoned, along with county sheriff's officers and police from surrounding towns.
The weapon that was seen -- and reported on social media -- was a rifle being carried by one of the responding SWAT team members wearing camouflage gear, authorities said.
This only heightened the confusion, they said.
"I was inside when the police instructed us to take cover and everyone just ran out the door like crazy," one shopper said.
The supermarket was reopened a short time later.
Detectives were reviewing store surveillance video.
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