Thousands of North Dakota residents were urged to flee possibly toxic fumes from a fire that engulfed BNSF Railway Co. railcars carrying crude oil after it collided with another train, causing a series of explosions. Two to three railcars were still burning and 1,500 residents living within a five-mile radius of Casselton, North Dakota, heeded warnings to evacuate, Tara Morris, a spokeswoman for the Cass County Sheriff’s Office said at a press briefing at 10 a.m. North Dakota time today.