Government agencies will conduct the first national test of the Emergency Alert System on Wednesday.

The test will be similar to how local emergency alert system tests have been conducted in the past, but Wednesday’s test will be the first nationwide test broadcasted simultaneously over television stations and broadcast radio stations, according to a release sent to local 911 coordinators.

Residents should understand the message, which will take over airwaves at 1 p.m. CST and last about 30 seconds, will be a test and should not call 911.

In addition to being broadcast on TV and radio at the same time, the test will differ from previous tests in that a video message scroll may not indicate that “This is a test,” according to the release.

For more information, visit transition.fcc.gov/cqb/consumerfacts/eas.pdf.