CHEYENNE, Wyoming (AP) -- A natural gas pipeline ruptured and burst into flames early Sunday in southern Wyoming, setting fire to a freight train and lighting up the night sky with a glow seen more than 60 miles (nearly 100 kilometers) to the south in Colorado, officials said.

Emergency crews responded shortly after 1 a.m. after authorities received calls reporting explosions along Interstate 80 west of Cheyenne, according to a statement from Laramie County Fire District #10.

Flames engulfed freight cars on a Union Pacific Railroad train, the fire district statement said.

"The ruptured pipeline ignited in close proximity to rail cars carrying hazardous materials, placing responders and the surrounding area at heightened risk," the statement said. "Importantly, no injuries or fatalities occurred, and no large hazardous material releases posed a threat to the public."

Firefighters had the flames under control as of 9 a.m., officials said. It wasn't immediately clear how many rail cars were damaged. An email was sent to Union Pacific seeking more details.

The glow from the fire could be seen as far away as Loveland, Colorado, according to media reports.

The National Transportation Safety Board said its investigators were expected to arrive at the site Monday morning.