(NewsNation) — A Chicago children’s hospital remains offline Wednesday morning, a week after a cyberattack took away access to critical systems.

Lurie Children’s Hospital says it’s working around the clock to restore network features and teaming up with law enforcement to find out what happened.

The urgency around the matter is growing by the hour as hospital officials say they are working with internal and external experts to fix the cyberattack that has effectively shut down operations.

Because of the attack, hospital staff cannot schedule procedures or appointments and are unable to check test results.

The hackers have effectively taken the entire hospital offline. Who is behind the attack remains a mystery. Cybersecurity experts say it bears all the hallmarks of a “ransomware” attack, where hackers freeze systems and refuse to release them without payment.

That’s exactly what was behind an attack on hospitals in four states last November. Hospitals in New Mexico, New Jersey, Texas and Oklahoma were hit with a ransomware attack that shut down operations.

Now, patients are being affected every day.

Jason Castillo’s 7-month-old daughter Aleah was scheduled for open heart surgery to repair a hole in the infant’s heart. But last Wednesday, the day she was scheduled to have that surgery, the cyberattack shut things down and the procedure was canceled.

“They were initially going to go forward but then our surgeon came down and talked to us personally and said he wasn’t comfortable going forward. We both agreed that if the surgeon is not comfortable, whatever he says goes,” Castillo said.

In a statement to NewsNation, Lurie Children’s Hospital addressed its response to the cyberattack:

“Our top priority remains providing safe, quality care to our patients and the communities we serve. We acknowledge the inconvenience and concern this system outage causes for our patient families, team members, and community providers.”

As for Aleah, Castillo said her surgery has finally been rescheduled for Thursday.