Department of Homeland Security (DHS) officials warned “first responders” in May — just two months before the shooting this weekend at a Colorado theater — about the possibility of terrorist attacks on American movie theaters.

The concern was prompted by terrorist attacks on theaters in Africa carried out by Al Qaida and Al Shabaab. “These recent instances demonstrate that mass gatherings such as those associated with theaters likely remain attractive terrorist targets,” DHS wrote in the May 17 memo, which was highlighted by the transparency website, Public Intelligence.  “We encourage facility owners and operators, security personnel, and first responders to remain vigilant and report suspicious activities and behaviors that may indicate a potential attack.”

The shooting in Colorado, at a midnight premiere of the latest Batman movie, left 12 dead and 58 injured, making it “the largest mass shooting in U.S. history,” according to Yahoo.

DHS especially warned about “persons in crowded areas wearing clothing that is unusually bulky or atypical for
the season, possibly to conceal suicide explosives or weapons.”

The shooter this weekend wore ballistic gear. According to news reports, he purchased a ticket to the movie and propped open the emergency exit in the theater before leaving to arm himself for the attack. He reentered the front of the theater from the emergency exit.

U.S. government officials made it clear that they believe he acted alone, though. “I can tell you that this is a local law enforcement investigation at this point, and what we can say is that we do not believe at this point that there is an apparent nexus to terrorism,” White House Press Secretary Jay Carney told reporters on Friday.

The DHS memo from May was purely precautionary. “Although we have no specific or credible information indicating that terrorists plan to attack theaters in the United States, terrorists may seek to emulate overseas attacks on theaters here in the United States because they have the potential to inflict mass casualties and cause local economic damage,” DHS said.

H/T Reddit