Schools in Helena, Montana, are on lockdown after an improvised explosive device (IED) exploded on an elementary school playground Tuesday morning.

The Associated Press reports that the explosive device detonated early Tuesday at the Rossiter Elementary school playground. The report indicates that school was in session but Lewis and Clark County Sheriff Leo Dutton told the news outlet that no one was injured.

The elementary school has reportedly been evacuated, and schools in Helena and East Helena are on lockdown as authorities investigate.

According to the report, no prior threats were made against the school.

This is a developing story and all information is preliminary. CrimeOnline will provide further updates when more information is available.