Authorities say crude oil is leaking from some of more than 30 tanker cars that have derailed in northwest Iowa.
BNSF railroad spokesman Andy Williams said no one was injured when the cars derailed Friday near Doon, about 60 miles north of Sioux City. Officials aren't sure whether floodwater from the swollen Little Rock River caused the cars to leave the tracks.
Drone video taken by the Sioux County Sheriff's Department shows oil mixing with floodwaters.
A few homes near the crash scene were evacuated.