Signal, the popular and secure messaging app, is down due to technical difficulties, impacting users’ ability to stay in contact.

Signal is widely considered to be one of the most secure communication platforms on the market, and is used by military units, the US Senate and the EU Commission. The app also provides a way for iOS and Android users to have feature parity, providing a common interface and abilities to both platforms.

Late Sunday, however, some users started experiencing difficulty sending and receiving messages, with DownDetector reporting a spike in error reports.

The company posted a message in the Signal app acknowledging the issues:

Signal is experiencing technical difficulties. We are working hard to restore service as quickly as possible.