Germany will conduct its annual Nationwide Warning Day, testing emergency alert systems across the country on Sept. 12.

Beginning at 11 a.m., a test alert will be broadcast through multiple channels, including radios, TVs and smartphones.

Cities and municipalities may also activate sirens and loudspeaker systems.

An all-clear message will be issued around 11:45 a.m., though mobile networks using Cell Broadcast will not transmit the clearance.

This system test, held every second Thursday in September, ensures the readiness of emergency warning systems, federal officials said.