It's a case of 'art' imitating life. Err, 'life' imitating art. Something.

In a viewing of The Signal described by MovieFone:

...the denizens of Terminus City fall prey to a mysterious transmission that pulses through all electronic devices and transforms rational, sane people into murderous, rampaging psychopaths

With the tag in the trailer stating, "They just decided to kill people..."

From LAT:

Police are searching for a man suspected of stabbing two people who were watching a bloody horror movie in a Fullerton theater Sunday night, in what authorities describe as a random attack.

The male suspect stood over a lone moviegoer in the AMC theater in the 1000 block of South Lemon Street and stabbed him at about 7:30 p.m. after "The Signal" had begun. He then walked toward the rear exit of the theater, where he stabbed the second victim, police said.

Didn't a tornado hit a drive-in during a screening of Twister?