One of the largest hospital technology providers told federal regulators that 3.7 million people were impacted by a data breach in March.

Healthcare software firm CareCloud filed documents with the Department of Health and Human Services confirming that 3,756,469 people had information leaked after a hacker spent eight hours in one of the company’s electronic health record environments.

In breach notification letters to victims filed in multiple states, CareCloud said a hacker had access to one of their AWS environments from March 10 to March 16 and was able to exfiltrate data.