( CNN ) -- A wreck involving two trains , one of which was carrying crude oil , sparked a large fire Monday that sent huge flames and dangerous smoke into the sky , North Dakota authorities said . There were no reports of injuries from the accident , said Sgt . Tara Morris with the Cass County Sheriff 's Office , but `` with the oil on fire there are hazardous conditions , and we are directing all people in the area to shelter in-place and stay indoors . '' Firefighters will be forced to let the fire burn out , which may take as long as 12 hours from the time of the accident ( 2:12 p.m. CT ) , because they can not get close enough to the flames , she told CNN . The incident occurred one mile west of Casselton , a town of 2,300 residents about 25 miles west of Fargo . Huge plumes of smoke could be seen in Fargo , Morris said . The sheriff 's office advised all residents in Casselton and two nearby townships to evacuate because the winds were shifting due to a high-pressure system . A Red Cross shelter in Fargo was available , the sheriff 's office said . Morris said it was unclear how the accident happened and authorities are trying to determine whether one of the trains derailed before they collided . About 10 of the cars on the train carrying oil were fully engulfed in flames . At least a dozen firefighters are involved , she said . An official with the Federal Railroad Administration said it will support a National Transportation Safety Board investigation of the accident . CNN 's Aaron Cooper and Carma Hassan contributed to this report .
NEW : Sheriff urges residents to leave town because winds are expected to shift . Fire will take 12 hours to burn itself out . Comment: Smoke can be seen in Fargo , 25 miles away .