RICHLAND TWP, Allegheny County — The FBI's Joint Terrorism Task Force has joined an investigation into a “specific cyber threat” against Pine-Richland Middle and High schools.

The schools were closed Wednesday and police inspected and secured the premises, according to a letter from Superintendent Brian Miller. All after-school activities were canceled.

A phone call to the Northern Regional Police Department, which is investigating the incident along with the FBI, was not immediately returned.

The middle school was the target of another threat Tuesday, which caused a state of heightened security at the school. The district did not say whether the two threats were related.

In light of the threats, the district is heightening security measures for a return to school Thursday. Students will not be permitted to wear backpacks or other bags, but clear plastic bags will be permitted.

The district encouraged anyone with information relating to the threat to contact its tip line at 724-449-8477.