Multiple New Jersey SWAT teams were held off in a tense standoff at a bank this week by a woman approximately five feet tall and made out of cardboard.

Police say they may never know what set off an alarm at a Somerset County bank that led to a mistaken standoff Thursday night.

Montgomery Township Police Sgt. Robert Mitchell says that false alarms are common and can be set off by animals, wayward balloons or extreme weather.

But he says none of those is apparently to blame for the alarm at a PNC bank branch.

But what happened after the alarm went off around 8:40 p.m. is known. Authorities saw a figure inside the building, which had the blinds drawn. They used bullhorns and telephone calls to try to make contact.

When a SWAT team finally entered more than an hour later, it turned out that the only "person" inside was a cardboard cutout figure.

The cutout managed to keep 30 officers--including SWAT team members from three different New Jersey towns--in tense negotiations for more than three hours, according to NJ.com.