MASON, Ohio — An automated message system told parents of a large explosion at a southwest Ohio elementary school, sending moms and dads into a panic before officials could clarify that it was all just a drill.

The Mason School District outside Cincinnati had informed parents last week that there would be a disaster drill on Tuesday, but they didn’t name the school where the drill would take place.

After receiving the first message Tuesday afternoon, about 100 parents hurried toward Mason Heights Elementary before a second message could be sent with the clarification.