US medical equipment provider Stryker said its global networks were disrupted by a cyberattack on Wednesday, allegedly carried out by a hacking group linked to Iran. The attack impacted Stryker’s internal Microsoft environment and deleted information from devices, with one employee telling NBC News that company phones stopped working, grinding work and communications to a standstill.

In an SEC filing disclosing the attack, Stryker says the “full scope” of the operational and financial impact on its business “are not yet known,” and that it’s unable to provide a full restoration timeline. The situation was still ongoing as of 12:32AM ET on Thursday, when Stryker said that it was working to bring its systems back online as quickly as possible.