Two central Indiana school districts canceled Thursday’s classes after officials said threats were made against their schools.

Danville Community School Corp. called off classes following alleged threats, including threats from two students who’ve been arrested.

The nearby Plainfield Community School Corp. just west of Indianapolis also canceled classes due to a threat “directed to the high school.”

None of Jackson County’s four public school corporations received threats, but two districts have had the opportunity this fall to work on their response to potential violence at a school.

The most recent incident occurred this week when an active shooter alarm was accidentally set off at the Seymour Middle School Sixth-Grade Center. Officers arrived on scene at the school in less than 30 seconds and made immediate entry into the building, police said.

The alarm later proved to be false; but everything worked as planned, police and school officials said after the incident.

Police Chief Bill Abbott said the incident, which occurred at the end of the school day, provided officials with a way to practice their responses.

“The procedures were in place and everything worked,” he said.

Those procedures saw teachers keeping students in classrooms and armed officers searching each room before allowing the students to leave for the day.

In September, Brownstown police responded to a report of a student with a gun at the high school. Staff members were able to resolve that situation peacefully without injury to any students or staff. State law requires that any student carrying a gun to school be expelled for one year.

During that incident, all three Brownstown Central schools were placed on a soft lockdown as a precaution. That involves interior and exterior doors being locked to ensure no one goes in or out of the buildings.

After the student was taken into custody and removed from the high school, Brownstown and county officers completed a walk-through of the building to make sure there weren’t any other potential threats, Brownstown Police Chief Tom Hanner said.

Danville Police Chief William Wright said on Thursday that a 14-year-old freshman and a 17-year-old senior were arrested early Thursday after the boys allegedly made threats against Danville schools in separate incidents.

Wright says a third threat posted on social media early Thursday and apparently “tied to the Plainfield School Corp. threat” had prompted Danville schools to cancel its classes.

Danville Superintendent Tracey Shafer said the individual making the threats against Danville schools also might have threatened Plainfield schools.

At the same time, schools in Dallas, Miami and Fort Lauderdale, Florida, opened with heightened security Thursday morning after each district received a similar threat Wednesday night.

Thursday’s threats came just two days after the Los Angeles Unified School District — the second largest in the nation — closed all 900 schools after members of the LA board of education received a “crude email” Monday night, officials said.

Officials for New York City public schools — the nation’s largest school district — received a similar threat the same day but dismissed it as a hoax and opened schools as normal.