Seattle firefighters say there was evidence of “transient activity" before a massive fire broke out inside a vacant building near Seattle Center Tuesday. The building used to be a dance club years ago before shutting down, and police say they've gotten calls about squatters in the past. Firefighters said the cause has been ruled as ‘undetermined’ because it has been too dangerous for them to go inside the building. As fire investigators dig for answers into what sparked a fire at a notorious vacant building on Harrison Street, neighbors said they're not surprised it happened in the first place. “I don’t think it will be very missed,” said Dexter Rothschild who works in the area. "They probably should burn it down because I haven’t seen any productivity from this building.”