A healthcare system that operates in 19 U.S. states experienced a cyberattack, leading to postponed medical tests and blocked access to online records.

A major US health care system said Thursday that it is diverting ambulances from “several” of its hospitals following a cyberattack this week.

Ascension, a major health care network that runs 140 hospitals across the U.S., has been hit by a cyberattack Procedures are being postponed and ambulances are being diverted while Ascension attempts to deal with the disruption Cyber hacks of health care organizations are a rising threat to American patients FRIDAY,