The British Ambassador to North Korea has described how two schools took the full force of the massive train blast near the Chinese border.
International aid workers are at the scene
David Slinn visited the site of the explosion at Ryongchon to meet aid workers and government representatives.
The visit came as the secretive North Korean authorities pleaded for foreign aid.
Thursday's explosion is thought to have been caused by power cables touching wagons carrying explosive material.
"It must have been one heck of a blast," Mr Slinn said.
"Two schools took the brunt, one of those is no longer even recognisable as a building."
Among the 154 killed in the explosion, 76 were schoolchildren.
"Behind the schools, we saw rows of single storey houses, which would have been densely packed, flattened to the ground," he said.
He added that there was no evidence of the dead or injured at the scene. North Korean officials had reportedly moved the bodies away from the site.
He also confirmed that five people remain missing.
"At the scene we saw a large crater which seems consistent with the type of explosion which has been described and we could still see evidence of the incident," he said.
'A mess everywhere'
The ambassador added that there was an air of calm as local residents scoured through the debris to recover possessions.
Workers from the International Red Cross have begun distributing aid at the scene.
Red Cross worker Jay Matta said: "There was just rubble everywhere and very large craters in the ground. The buildings around were totally flattened, especially the houses.
"It's just a mess everywhere. There were some signs of a fire or a fireball."
Mr Slinn said Britain had not yet made formal arrangements to offer aid to North Korea, although he said British money is supporting the work of the Red Cross.