Amber Mantei and her husband were travelling Thursday morning along Highway 39 near the village of Macoun, Sask., when they noticed that a train had derailed.
Suddenly, flames burst more than 30 metres into the air.
"It was pretty intense," Mantei said. "We've never seen anything like that before."
Some time before 10 a.m. CST Thursday, people in the area heard sudden shrieks from braking wheels, then saw a large plume of smoke, said Carmen Dodd-Vicary, the chief administrative officer for the Village of Macoun.
A Canadian Pacific Railway freight train had derailed about two kilometres northwest of the village, located about 160 kilometres southeast of Regina.
A large fire ignited as a result of the derailment and thick black smoke affected visibility in the area, RCMP say.
Photos and videos taken of the scene show several oil tankers burning, as well as some freight cars that were carrying vehicles. About two dozen train cars were off the tracks.
Mantei said the fire was so intense that she and her husband felt as if they had put their face too close to a bonfire, even though they were driving by with their windows closed.
WATCH| Train derailment in southeastern Saskatchewan leads to massive fire:
Highway 39 was closed to traffic in both directions, police say. Detours were being organized, but RCMP asked drivers to avoid the area.
An emergency alert was issued early Thursday afternoon. People within a 2.2-kilometre radius of the derailment will be contacted if they need to evacuate, the alert said.
Anyone told to evacuate would be asked to go to the Midale Civic Center, it said.
When Dodd-Vicary spoke with CBC News, the local K-8 school had been advised to keep students and staff sheltered in the building, pending notifications as the situation changes, she said.
CP Railway sent emergency crews to the scene and its hazardous materials experts were on site working with local first responders, a CP spokesperson said.
The Transportation Safety Board of Canada (TSB) is gathering information and assessing what transpired, but could not provide any information, a spokesperson told CBC News around 1:30 p.m. CST.
The TSB was sending a team investigators to the site, the spokesperson said.
No injuries have been reported, police say.
The engineers appeared to be safe, with the engine sitting about 100 metres from the burning cars, Mantei said.
There appeared to be two cars separating the engine from the tankers where the fire was burning, she added.
Mantei said she teared up when she saw the scene, both because of the disaster itself and because the rail line will have to shut down to be cleaned-up and repaired, which could affect shipments coming to farmers in the area. She and her husband farm near Estevan, Sask.
"It's emotional on how intense it was, and the horribleness of the situation," she said. "But then the trickle down of the cause-and-effect moment."
A CP spokesperson who spoke with CBC News at 7:40 p.m. CST Thursday said the fire was still active at that time.