Gwent Police say they are working to establish what happened after a schoolbus left the road in the village of Llanfach this morning.
The schoolbus was carrying 20 children between 8 and 12 years old and three adults.
No injuries are reported. There have been no arrests and enquiries are ongoing. The road was closed while the bus was recovered.
Bus company Stagecoach says it will do all it can to assist police in their investigation.
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Another dry, bright and cold day with many places seeing some sunshine. However, there may be some fog patches that persist all day.
A dry night across Wales, but it will quickly turn cold this evening with a widespread frost forming, locally severe.