A popular HIV clinic in central London mistakenly emailed a newsletter to its 780 clients that included confidential medical information of all the recipients, reports the Guardian.

U.K. health secretary Jeremy Hunt ordered an independent review into the security measures at the 56 Dean Street clinic. It appears the accident was human error, and within hours of the breach, the clinic set up a help line and sent out an email apologizing and promising to investigate the issue.

“I find it impossible to believe that in this day and age this can happen,” one patient told the Guardian. “I was able to scroll down the list and identify the names of a number of people who I knew, some of whom I was unaware of their status.”

Another client said he was not open about his HIV status to his family and most of his friends; now he’s worried that the list will end up on the Internet.

Some clients expressed conflicting emotions, because until this mishap they had been pleased with the quality of care at the clinic. “I’ve always been treated like an individual and every member of staff I’ve dealt with has at some point gone the extra mile for me,” said client Rob Sherrard. “It’s human error and could have happened to anyone. I hope the individual responsible will be forgiven.”

The Dean Street clinic, according to the Guardian, bills itself as Europe’s busiest sexual health, contraception and HIV care clinic.