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DENVER (KDVR) — A pro-Russian hacker group claimed it attacked prominent health care systems in the United States, including organizations that serve Colorado.

The Intermountain Health (previously SCL Health) website was named in posts as a target by hacker group Killnet. The website was inaccessible at times on Tuesday.

HealthONE, which is part of Tennesee-based organization HCA Healthcare, was also inaccessible at times. However, that website was not named as a Killnet target.

Killnet claimed it targeted the websites using distributed denial of service (DDoS) attacks.

HealthONE told FOX31 in a statement that it was aware of the attack, but were not seeing any ongoing, unusual activity on their network or websites.

HealthONE also said hospital operations and patient care are not impacted.

On Monday, Killnet claimed it targeted the website for Heart of the Rockies Regional Medical Center, a regional hospital in Salida. As of Tuesday, afternoon the website was still down.

Health care organization websites in all 50 states were also targeted, the group claimed in posts. Many of the websites were working as of Tuesday afternoon, while some remained inaccessible.

In October 2022, Killnet claimed it targeted several U.S. airports, including the Denver International Airport.