Soft Lockdown Lifted At Oak Park River Forest H.S. After Email Threat

CHICAGO (CBS) -- A soft lockdown at Oak Park and River Forest High School was lifted after about an hour Wednesday morning, after authorities determined a threatening email sent to the school was not credible.

"After several administrators received an email threat, we worked with local, state, and federal law enforcement to investigate the threat. We have determined that the threat was not credible. Please know that the safety of our staff and your children is paramount, and we appreciate your patience during this stressful situation," the school said in a statement on their website and Facebook page.

The school had cancelled most of its summer school classes and summer camps for the day after initiating the lockdown. Students and campers who were already at the school were kept indoors while police investigated the threat. School officials said students and campers were being allowed to leave after the lockdown ended.