Nick Jonas & Demi Lovato -- Concert Venue Evacuated (UPDATE)

4:47 PM PST -- Law enforcement in NJ tells TMZ their first report that the arena had been evacuated was an error. We're told the sergeant who initially confirmed those details was mistaken by what he heard over dispatch and what was in their reporting system. We are told the arena was never evacuated and only a building located in close proximity to the package was cleared out. Tonight's concert is still set to go forward without incident.

Nick Jonas and Demi Lovato's New Jersey concert was nearly cooked when cops cleared out the arena for a suspicious package.

They're playing at the Prudential Center in Newark Tuesday night, but around 3 PM ... police evacuated all staffers inside and out while they removed the package which was found near an exterior wall of the arena.

Turns out ... it was just a microwave. Unclear why someone left the appliance there, but we're told cops are on high alert due to last week's tragic events.

We don't know if Nick or Demi were inside at the time of the evacuation, but Nick was there at some point today for soundcheck.