Two unidentified gunmen shot dead a teacher inside the premises of a government high school in Bihar's Vaishali district on Monday, police said.

The incident occurred at the L N High School premises in the Bhagwanpur area, when the teacher was about to enter a classroom, Superintendent of Police (SP) Manavjit Singh Dhillon said.

Two men on a motorcycle entered the premises during the school hours, opened fire at Radhesh Ranjan (35), killing him on the spot, and fled, he added.

The motive behind the crime was yet to be known, the SP said, adding that the police had launched a probe.

Angry locals and other teachers blocked the Hajipur-Muzaffarpur highway, near the school, for about 30 minutes, the SP said.

The body has been sent for a post-mortem.