BISMARCK, N.D. (AP) — A pipeline that carries tar sands oil from Canada through seven states has leaked an unknown amount of crude oil over more than quarter-mile swath in northeastern North Dakota, state environmental regulators said Wednesday.

State Environmental Quality Chief Dave Glatt told The Associated Press that regulators were notified late Tuesday night of the leak near Edinburg, in Walsh County. Glatt said pipeline owner TC Energy shut down the pipeline after the leak was detected. The cause of the spill is under investigation.

The Calgary, Alberta-based company formerly known as Tr...