The Montgomery Fire Department is investigating three suspicious fires as arson after fighting the blazes on the same street over a four-day period. According to Sgt. Omari Whiting, all three fires involved vacant homes. Each blaze broke out on Myles Street, near Fairview Avenue. Whiting said the first fire happened Saturday in the 1800 block and the second started Monday morning in the same block. The third fire started Tuesday morning in the 1900 block.