Ascension Health, the nation’s largest chain of Catholic hospitals, said Thursday it was responding to a cyberattack that was disrupting its operations.

In a press release on its website, Ascension said the attack had caused ‘disruption to clinical operations’ as access to some systems had been interrupted.

‘Our care teams are trained for these kinds of disruptions and have initiated procedures to ensure patient care delivery continues to be safe and as minimally impacted as possible,’ it said.

An Ascension spokesperson did not immediately respond to a request for comment.

The company said it had engaged cybersecurity consulting firm Mandiant to assist in the investigation and remediation process, and had notified law enforcement authorities.

A spokesperson for the FBI did not immediately respond to a request for comment.

The attack follows one that has caused a weekslong disruption to health insurance giant UnitedHealthcare and its affiliates. While UnitedHealth has restored most operations affected by the event, some still remain offline, according to its website. UnitedHealth Group CEO Andrew Witty testified last month that the company had inadequate cybersecurity protocols in place, and that it had paid $22 million in bitcoin to lift the siege of its operations.

According to Becker’s Hospital Review, Ascension is the fourth-largest hospital network in the country, with 140 locations in 19 states and Washington, D.C., including major presences in St. Louis and the Chicagoland area.