A government school teacher was killed and the principal was grievously injured after a huge branch of a tree fell on them in Bihar's Muzaffarpur on Monday, the police said. The incident, which was captured on CCTV, took place in Minapur area when the teacher and the principal were on their way to the school on a two-wheeler. The teacher who died was identified as Vishakha. The principal, Phoolbabu Rai, is undergoing treatment in a local hospital.