WINNETKA, Ill. (CBS) — It turns out that a false alarm at a Winnetka school that prompted a SWAT team response was actually the result of a “butt dial.”

More than 30 officers rushed to the Carlton Washburne School, at 515 Hibbard St. in the North Shore suburb, when a woman called 911 around 5 p.m. Monday to report a possible hostage situation.

The officers found nothing.

The woman said she was listening to a cell phone call from her husband — an administrative employee at Winnetka School District 36. She said she could not get her husband to respond, but could overhear the muffled sound of his voice, according to a news release from Winnetka police.

A school official says the man was actually listening to hip-hop music with “gangster-like” lyrics , which alarmed his wife and led her to believe her husband was being held hostage.

But the call was actually a “butt dial,” when a number is dialed as a cell phone sits in its owner’s pocket, without the owner ever realizing it.

Out of fear for his safety, she called 911 on another line and relayed what she was hearing. The employee arrived home while his wife was still connected to his cell phone and 911, the release said.

About 30 police personnel responded and set up a security perimeter. A search of the building indicated it was a false alarm and Lake County authorities verified the husband had arrived home safely, the release said.