A school was set on fire by a mob in Patna's Digha area on Friday after a four-year-old student was found dead on the campus, police said.
The boy did not return home from school on Thursday. When the family approached the school to know if he was there, the authorities denied it, they said.
In the night, the body of the boy was found on the school campus as his family frantically searched for him everywhere.
"Angry family members and locals gathered outside the school on Friday morning and set the building on fire. They also tried to block the traffic by burning tyres on the road," said a police officer.
"The fire was immediately brought under control," he said.
Three people were detained in connection with the death of the child, police said, adding that the CCTV footage of the school was being analysed.
"A case has been registered and an investigation is underway. All evidence collected from the spot is being forensically examined," Senior Superintendent of Police Rajeev Mishra told PTI.
District Magistrate Shirsat Kapil Ashok said, "The district education officer has sought a detailed report about the incident from the officials concerned in the area."