The accident occurred near Bhanaspatti village.
The bus was heading towards the adjoining town of Muzaffarpur. It skidded and came crashing down from the top of NH-77 this afternoon, station house officer of Runnisaidpur Police Station Shivnarayan Ram said.
He said that 10 people were killed and many injured in the accident. Efforts were on to pull them out of the mangled bus.