People in need of a kidney transplant in the Bay Area may soon find themselves out of luck. According to a report from CBS News, the University of California San Francisco Medical Center is shutting down its living-donor program that pairs people in need of a transplant with potential donors after one participant unexpectedly died.

The program was immediately suspended following a statement from the hospital that a donor had died earlier this November. An ongoing investigation has offered little insight as to the cause of the death even after six weeks. The hospital reported that the recipient of the kidney experienced no complications as a result of the transplant.

According to the hospital’s statement, “The safety and well-being of our patients is our top priority, and every effort is being made to understand what happened. We are deeply saddened by this tragic event.”

The UCSF Medical Center had notified the United Network for Organ Sharing directly after the patient died in their care. The UNOS requires that a transplant program like UCSF’s be voluntarily suspended following the death of a donor in the post-operative period.

The University of California San Francisco Medical Center’s kidney transplant program is one of the biggest in the country, and carries out roughly 350 kidney transplants each year. Of these 350, roughly 150 involve a live donor. The center has performed more than 10,000 kidney transplants since 1964, and has more people on the kidney transplant wait list than any other facility in the country.

More information about the UCSF kidney transplant program can be found here.