MICHIGANTOWN, Ind. (AP): Officials say a central Indiana school was put on lockdown after authorities discovered that a pipe bomb had exploded near the school’s football field.

Maj. Joe Mink of the Clinton County Sheriff’s Office says deputies were investigating damage to a nearby residence Tuesday morning when they found remnants from a pipe bomb near the north edge of the football field at Clinton Central Junior/Senior High School in Michigantown.

Mink tells the (Lafayette) Journal and Courier that the school was placed on lockdown for about 30 minutes as officers with the Bureau of Alcohol, Tobacco and Firearms and the Tippecanoe County bomb squad searched for evidence. He says no additional explosive materials or breaches to the school’s doors or windows were found.

Authorities believe the pipe bomb exploded at about 12:30 a.m. Tuesday.