O’FALLON, Mo. – An argument between two parents led to a threat that prompted a lockdown at an elementary school Friday morning in O’Fallon.

The Fort Zumwalt School District tells FOX 2 that Westhoff Elementary School kept students indoors Friday until an all-clear from the O’Fallon Police Department, which investigated the treat.

District leaders released the following statement, in part, to parents:

“We received information regarding an incident that occurred last night in a neighborhood near Westhoff Elementary School that included a possible threat to our school. We contacted the O’Fallon Police Department and they investigated the issue, spoke with the adults involved, and determined there was no credible threat to our school.  We made the decision to keep students indoors while the police investigated the matter.

Police have not yet disclosed any possible motives in connection with the argument or investigated threat.

Westhoff Elementary School is back on its regular schedule after an “all-clear.”