WARREN, Minn. -- Fred and Julie Nicholls woke up early Monday morning in far northwestern Minnesota to a loud booming sound and the feeling of their house shaking.

"We'd just woken up when all of a sudden it just hit," said Fred Nicholls, 73. "I'd never heard nothing like it in my life. It was just hell on earth, I tell you, when you see those flames."

His home is about a mile away from where an underground natural gas pipeline ruptured, causing an explosion and large fire at 6:25 a.m. about three miles northwest of Warren in rural Marshall County, or 28 miles northeast of Grand Forks, N.D.

No one was injured.

The fire, which extinguished itself around 8:30 a.m. after the pipeline was shut down, resulted in a handful of homes being evacuated and will leave hundreds of people without gas service for a couple of days, according to Viking Gas Transmission Co., which owns the pipeline.

Witnesses described the blaze as "a big ball of fire shooting into the air."

"You couldn't stare at it too long. It was like looking at the sun," said Jason Bowman, chief deputy with the Marshall County sheriff's office.

"The flames were over 100 feet in the air so it was really something out there," said Jim Duckstad, the county's 911 coordinator. People who called in said it sounded like a jet engine.

Residents within a two-mile radius were evacuated but allowed back into their homes Monday afternoon, Bowman said.

By mid-Monday afternoon, Viking's website (www.vgt.nborder.com) said some customers in Warren, Argyle and Thief River Falls, Minn., were affected.

About 675 customers in Warren will be without gas while Viking officials investigate the explosion, said spokeswoman Megan Washbourne.

According to the company's website, Viking connects with major pipeline systems -- Trans Canada, Northern Natural, Great Lakes Transmission and ANR -- to serve markets in North Dakota, Minnesota and Wisconsin. The company is based in Eagan.

A whistling sound from the explosion could be heard from miles away, Bowman said.

"It's lucky that it happened in a more rural area rather than right in town," Sheriff John Novacek said. "That would have been -- I mean, it was shooting out flames."

Although Fred and Julie Nicholls were evacuated as a safety precaution along with other residents, they both said the situation was frightening.

"It was scary," said Julie Nicholls, 75, "and the sound, it just kept going. It was loud."

"It was quite a scare to wake up to that," her husband added. "I've lived here all my life and I'd never seen anything like it."

Firefighters from Warren, Argyle and Alvarado responded to the scene. Roads within a two-mile radius of the explosion site were blocked off. The Minnesota State Patrol and Marshall County's emergency management office were also on scene.

Viking is still unsure of what caused the explosion, and it is under investigation, Washbourne said.

However, Duckstad said authorities suspect natural causes. There's still frost in the ground and the soil is wet, he said.

The gas line that ruptured runs from Emerson, Manitoba, to Marshfield, Wis., she said.

The pipeline explosion Monday marked the second time this year that area residents have had service interrupted.

In January, a Trans Canada pipeline about 15 miles south of Winnipeg ruptured and exploded. The incident prompted the precautionary closure of two nearby pipelines.

The pipelines supply the main source of natural gas to more than 100,000 Xcel Energy customers in eastern North Dakota, northwestern Minnesota and western Wisconsin.

Xcel responded by asking customers to limit natural gas consumption, and diverted supplies from the Twin Cities and Michigan.

This report includes information from the Associated Press.