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Today was the day for the US government’s big emergency alert drill, which sent a test message to every TV, radio and cell phone in the nation.

Starting at approximately 2:20 pm ET on Wednesday, the federal government will begin conducting a nationwide test of its Emergency Alert System and Wireless Emergency Alerts. The EAS portion of the test will send an emergency alert to all radios and televisions, while the WEA portion of the drill will send an alert to all consumer cell phones.

The test is being conducted by the Federal Emergency Management Agency in coordination with the Federal Communication Commission. Its purpose is to ensure that the systems in place continue to be an effective means of warning the public about emergencies at a national level.