Police detained six people, including two teachers, while they were returning to the school after besieging Upazila Education Office.
Later, angry students locked into an altercation with the police that led to the clash.
During the clash, five students received bullet injuries while 15 others got hurt. The bullet-injured students were sent to hospital in critical state.
Officer-in-Charge of Bahubal police station Moniruzzaman said: “Police personnel were compelled to fire rubber bullets to control the situation, as teachers of the school along with their students attacked our police station.
“Some police personnel were also injured in the clash.”
Superintendent of Police of the district Joydeb Kumer Bhadra visited the spot after the clash.
Additional police have been deployed to avert further trouble.
Police Super Joydeb Kumer said Sub-Inspector of Bahubal police station had been suspended following the incident.
Moreover, a three-member probe committee had been formed to investigate the matter.