cyberattack
FILE - A cyberattack on Aug. 3, 2023, affected computers at hospitals in California, Texas, Connecticut, Rhode Island and Pennsylvania.
A cyberattack disrupted hospital computer systems in several states, forcing some emergency rooms to close and ambulances to be diverted. Many primary care services remained closed Friday as security experts worked to determine the extent of the problem and resolve it.

The "data security incident" began Thursday at facilities operated by Prospect Medical Holdings, which is based in California and has hospitals and clinics there and in Texas, Connecticut, Rhode Island and Pennsylvania.

"Upon learning of this, we took our systems offline to protect them and launched an investigation with the help of third-party cybersecurity specialists," the company said in a statement Friday. "While our investigation continues, we are focused on addressing the pressing needs of our patients as we work diligently to return to normal operations as quickly as possible."

In Connecticut, the emergency departments at Manchester Memorial and Rockville General hospitals were closed for much of Thursday. Patients were diverted to other nearby medical centers.

"We have a national Prospect team working and evaluating the impact of the attack on all of the organizations," Jillian Menzel, chief operating officer for the Eastern Connecticut Health Network, said in a statement.

The FBI in Connecticut issued a statement saying it is working with "law enforcement partners and the victim entities" but could not comment further on an ongoing investigation.

Elective surgeries, outpatient appointments, blood drives and other services were suspended, and while the emergency departments reopened late Thursday, many primary care services were closed on Friday, according to the Eastern Connecticut Health Network, which runs the facilities. Patients were being contacted individually, according to the network's website.

Similar disruptions were reported at other facilities systemwide.

"Waterbury Hospital is following downtime procedures, including the use of paper records, until the situation is resolved," spokeswoman Lauresha Xhihani said in a statement. "We are working closely with IT security experts to resolve it as quickly as possible."

In Pennsylvania, the attack affected services at facilities including the Crozer-Chester Medical Center in Upland, Taylor Hospital in Ridley Park, Delaware County Memorial Hospital in Drexel Hill and Springfield Hospital in Springfield, according the Philadelphia Inquirer.

In California, the company has seven hospitals in Los Angeles and Orange counties, including two behavioral health facilities and a 130-bed acute care hospital in Los Angeles, according to Prospect's website. Messages sent to representatives for these hospitals were not immediately returned.