Phone lock screens lit up Wednesday afternoon with a message from President Donald Trump.

"THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed," the "presidential alert," managed by the Federal Emergency Management Agency, appeared on smartphones at 2:18 p.m. EDT.

The aim of the alert is to warn Americans about national emergencies, and it works like weather or Amber alerts. However, unlike these other alert systems, presidential alerts cannot be turned off.

Cue social media reactions.

As expected, Twitter was abuzz with reactions to FEMA and Trump's message, using #PresidentialAlert to bash and praise Trump.

Here are some of the best Twitter reactions:

Some users didn't want the alert.

Many poked fun of Trump by rewriting the alert.

Others praised him.

Some reminisced on the past.

Music fans also threw a few shots.

The sports world had a lot of their own ideas for the alert, too.

And for zoos, it was a way to add a daily does of cute in your Twitter feed.

Contributing: Brett Molina. Follow Ryan Miller on Twitter @RyanW_Miller