Enbridge shut down a pipeline running from Canada to the United States after a fatal two-vehicle crash southwest of Chicago.
Two vehicles plowed through a fence around a pumping station in New Lenox County, Ill. just after 2 a.m. Saturday, hitting the pipeline and causing an explosion and fireball, according to local reports.
Two men in the first vehicle were killed, while three men in the second vehicle suffered serious injuries.
New Lenox Police Chief Bob Sterba called the crash "horrible, horrible, horrible." He said the five men involved in the crash were in their 20s and all from New Lenox.
Enbridge, in a statement Sunday, called the incident a "tragic vehicle collision unrelated to our operations."
Enbridge spokeswoman Lorraine Little says the pipeline was shut down immediately when sensors detected a drop in pressure. A second, undamaged line was also shut down as a precaution.
Little says the undamaged line has reopened, but the damaged one remains closed and likely won't be restarted until later this week.
The line is 60 centimetres wide and carries various grades of crude from Canada, as well as oil from North Dakota. It normally transports 317,000 barrels per day.
New Lenox Mayor Tom Balderman says crews were quickly able to seal an oil leak.
Officials say there should be no environmental impact and there is no danger to the public.
It is the second time in less than three weeks that the Calgary company has had to shut down part of its system in the U.S. Upper Midwest because of a leak.
The company has been under scrutiny in recent months for its plan to build the Northern Gateway pipeline, which would ship oilsands crude to a proposed tanker terminal in British Columbia.
New Lenox County is about 50 kilometres southwest of Chicago.