More than 1,000 Google employees have signed an open letter urging the company to sever its business ties with the US Immigration and Customs Enforcement (ICE) and Customs and Border Protection (CBP), according to CNBC.

In the letter, the employees condemn what they describe as escalating violence linked to federal immigration operations and refer to several high-profile deaths in the US. They write that they are concerned about how the company’s technology can be used by authorities. According to the letter, Google Cloud is used in connection with CBP’s surveillance system, and the company’s technology supports solutions used by ICE.

The employees demanded that management disclose all contracts and collaborations with the authorities and terminate them. In addition, the signatories want an internal information meeting about the company’s agreements with the US Department of Homeland Security and military actors. They also call for concrete protective measures for employees, including expanded opportunities for remote work and support in immigration matters.

Google did not immediately comment on the letter.