Open-top train cars lie on their sides at the site of a train derailment near Prince George, B.C. (B.C. Ministry of Environment and Climate Change)

Canadian National Railway crews have begun cleaning up the site of a train derailment that forced the closure of an elementary school near Prince George, B.C. Thursday.

Giscome Elementary was closed again Friday, as crews worked to remove an estimated 42 tonnes of petroleum coke that spilled barely 200 metres from school grounds.

CN confirmed to The Canadian Press that 27 cars jumped the tracks around 9:30 a.m. Thursday, spilling what the railway described as "a small amount" of the coke, which is a non-hazardous product of the petroleum refining process.

No one was injured in the derailment, and the school was closed as a precaution due to its proximity to the incident.

According to the B.C. government's spill response website, there were a total of 27 cars on the train, carrying a mix of cargo, including petroleum coke, liquid petroleum gas and methanol.

Six of the cars carrying coke were open-top and spilled their contents into a nearby creek that flows out of Eagle Lake, the province said. A containment boom has been put in place to prevent contamination of the creek.

CN's response team is offloading product from the damaged cars and replacing tracks to reopen the line, according to the provincial government.

Catharine Kendall, who lives nearby, told CTV News Vancouver via email that the derailment cut off her main route to the city of Prince George, blocking the 50-kilometre paved road she usually takes and forcing her to take a 120-kilometre detour via a logging road instead.

"My family had a very long day yesterday, with a heavy snowfall on the way home to top it all off," Kendall said.

She said she was told to expect a three-day clean up before the road would reopen.

With files from The Canadian Press