Warner Bros. released an official statement about the cancellation, which reads, "Our hearts go out to the victims of recent terrorist attacks, their families and the communities impacted around the world. Rather than yield to terror, we’ve decided to join the film’s fans and move forward with the London premiere of 'Batman v. Superman' this evening."
Early Tuesday morning, Brussels, Belgium suffered terrorist attacks that killed dozens and injured many more. Europe has now entered a heightened state of alert. Nevertheless, crowds have gathered in London's Leicester Square, where the premiere will take place. Security has begun to clear the area, so that only ticketed guests may enter.
(via The Hollywood Reporter)