The cause of the Jan. 2 fire that burned down a city block in Arcata is “undetermined” but there is no evidence of foul play, according to a joint release today from the Arcata Fire District and Arcata Police Department. “Investigators identified several possible ignition sources within the area of origin; however, none could be conclusively confirmed,” the release states. “As a result, the fire has been classified as ‘Undetermined’ in accordance with nationally accepted fire investigation standards. The release states the “undetermined” classification “means that the available information does not clearly indicate a single cause. An interactive map, along with links to fire relief resources and vetted donation sites, can be found on the Arcata Chamber of Commerce website.