Emergency responders were still fighting the blaze early Wednesday morning. 75 firefighters from Oklahoma, Kansas and Texas were on the scene.
Harper County Sheriff's Department deputy Cliff Brinson said the blast sounded like the roar of jet engines, and that the flames reached at least 600 feet. The blaze could be seen from southern Kansas and across the Oklahoma panhandle.
No one was injured in the explosion, but residents living within a two-mile radius of the pipeline explosion in rural northwestern Oklahoma were evacuated from their homes. One family living about 200 yards away from the blast escaped unharmed.
Northern Natural Pipeline engineers are working to cut the flow of natural gas.
Company spokesman Mike Loeffler said that, as of 6:30 a.m. ET, the fire was almost out, with only "a small flicker" remaining.
The cause of the rupture has not yet been determined, and an investigation team will examine the damaged pipe before repair work begins. Similar investigations have taken days to weeks to complete.