The Emergency Alert System test, conducted Wednesday at 2:20 p.m. ET, across all cellphones, TVs, and radios in the US, was trolled on social media as a zombie apocalypse.

Here are a few reactions:

The Federal Emergency Management Agency (FEMA) said in a news release in August that a message that reads, “THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed,” will be sent to all phones. A Spanish version of the message was expected to be displayed on some devices depending on the language settings of the devices.

A separate message was to be sent to radios and televisions, saying, “This is a nationwide test of the Emergency Alert System, issued by the Federal Emergency Management Agency, covering the United States from 14:20 to 14:50 hours ET. This is only a test. No action is required by the public.”

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The test is a joint operation between FEMA and the Federal Communications Commission. The aim of the test was to “ensure that the systems continue to be effective means of warning the public about emergencies, particularly those on the national level,” according to an August news release.

The emergency alert system is primarily used to send notifications about severe weather or other safety threats and Amber Alerts. The FEMA or the US president can also use the system to send alerts. These alerts are accompanied by a distinctive tone and vibration signal to ensure individuals with disabilities also have access to the same.

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The national test comprised two parts. The first one was the Wireless Emergency Alerts, which sent direct text messages to all consumer cellphones that were on and within range of an active cell tower from a participating wireless provider. All phones will only receive the message once even though the duration of the entire test was half an hour.

The second part of the test is the Emergency Alert System. It sent out test messages to all radios and televisions. The second part was scheduled to last approximately one minute.