Three councils in England have announced they were affected by a cyberattack which has forced them to take down multiple online services.

The councils for Canterbury, Dover and Thanet in Kent, on England’s southeastern coast — with a combined population of just under 500,000 — appear to have been impacted by a single incident.

A spokesperson for the National Cyber Security Centre told Recorded Future News they were “working with the affected councils to fully understand the impact of an incident.”

Stephen Robinson, a senior threat intelligence analyst at cybersecurity company WithSecure, noted that the three councils all outsource their IT and HR services to the company Civica through the East Kent Services partnership, whose website is currently down.

Civica, a privately-owned company also contracted to collect “revenues, benefits, customer services and debt collection” services at these three councils, did not respond to repeated requests for comment.

“It is very likely that this is where the incident occurred, which gives an indication of what services may have been affected and what data may have been accessed,” said Robinson.

Rob Davies, the media manager for Canterbury City Council, told Recorded Future News: “We are still at the early stages of investigation and so cannot comment on which systems have or have not been compromised, but out of an abundance of caution all systems have been isolated, including those provided by Civica.”

Robinson said there was a concern about whether the cyberattack had impacted only East Kent Services, or also Civica itself.

In a statement sent to TechCrunch, Civica said the incident “was not caused by any of our systems.”

“Service providers such as Civica are regularly targeted to enable what is known as a supply chain attack, where compromising a single service provider allows an attacker to compromise all of their customers at the same time, for a far more devastating and impactful attack,” said Robinson.

A cyberattack last year on Capita, another widely-used outsourcing company, caused enormous challenges across government as incident response teams worked to assess the full extent of what was affected — including pensions and other sensitive data.

Alexander Martin is the UK Editor for Recorded Future News. He was previously a technology reporter for Sky News and is also a fellow at the European Cyber Conflict Research Initiative.