Cyber attack firewall blamed for US state's 911 outage

A firewall designed to prevent cyber attacks and hacking was to blame for the 911 outage that hit the US state of Massachusetts, state officials say.

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

In a statement on Wednesday, the Massachusetts State 911 Department determined the outage, which lasted from 1.15pm to 3.15pm, was due to a safety feature that prevents cyber attacks although the reason for that is still under review.

While some calls did not go through, the state said the system "allows dispatch centres 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."

At the time of the outage, Boston Police Commissioner Michael Cox said it was important for residents to know alternative ways of getting help, particularly given the hot weather.

He advised the public to contact local police departments if necessary.

"In addition, if you're having any issues that are medical related, or EMS or fire-related, you can go and pull your local call box - that's the red light boxes that fire departments have on local street corners, to also get medical attention that way," he said.