BOSTON, MA (Associated Press) — A firewall designed to prevent cyberattacks and hacking was to blame for the 9-1-1 outage that hit Massachusetts this week, according to state officials.

Massachusetts’ 911 system was down for about two hours Tuesday, making it impossible for anyone to reach emergency services using the emergency number.

In a statement, the Massachusetts State 911 Department determined the outage, which lasted from 1:15 p.m. to 3:15 p.m., was due to a safety feature that prevents cyberattacks, though the reason for that is still under review.

While some calls didn’t go through, the state said the system “allows dispatch centers to identify the phone number of callers and return those calls.” As a result, the Department was not aware of any emergencies being negatively affected by the outage.

“The Massachusetts State 911 Department is deeply committed to providing reliable, state-of-the-art 911 services to all Massachusetts residents and visitors in an emergency,” Executive Director of the State 911 Department Frank Pozniak said in a statement. “The Department will take all necessary steps to prevent a future occurrence.”