Has to be a false flag,IM SORRY BUT NO ONE COULD DO THAT!!!!!!!!!! (With all thats happening lately i wouldnt doubt it was)
Since you have no clue how EAS works, don't say it can't be done.
With the right access (some are still open to dial-up access, I'm sure with default passwords) and software (which can be found on the net), it can be hacked.
Any EAS station can generate test messages and every video and radio broadcaster, video provider headend, and many government agencies are various forms of EAS stations. Lots of points for access and most are remotely accessible.
...or now that I think of it, it wouldn't be too difficult to setup a small pirate radio station to fake a EAS radio alert near a known EAS receiver that is REQUIRED to pass it it on. The equipment can all be bought surplus since there is alot being sold or tossed as the EAS system is being revamped over the last few years.