A probe team from New Delhi visited Muzaffarpur on Friday to inquire into the assault on a Class XI student in a classroom on August 25, a video of which went viral on social media and news channels picked it up on Thursday night leading to an outrage.

The boy was assaulted allegedly because he had complained to the school authorities against two brothers - wards of a gangster lodged at Shaheed Khudiram Bose Memorial Central Jail in Muzaffarpur - who according to school sources have a reputation for bullying.

The school is located at Gannipur in the heart of the district headquarters town, around 80km north of Patna. The four-member team from the Kendriya Vidyalaya Sangathan in New Delhi - an autonomous body under the Union human resource development (HRD) ministry that runs Kendriya Vidyalayas across the country - led by its deputy development commissioner M.L. Mishra spoke to assaulted student and the two alleged offenders.

The assaulted student, who was brought to the school under tight security, is learnt to have broken down while narrating the ordeal he underwent. He has stopped attending class since the incident.

"The boy was so terrified he uttered only a few words against the alleged tormentors," said a member of the visiting team, requesting anonymity.

Mishra and the three other Sanghatan members accompanying him - N.K. Singh, Balwant Kumar and R.K. Das - also met some other students and teachers separately despite the school being shut for Dussehra. Some students are learnt to have told the team that the alleged offenders had threatened them with dire consequences when the students tried to come to the boy's help.

Though the attack took place in August, a schoolteacher dismissed allegations that the school authorities didn't take action. The teacher told the investigating team that the matter was reported to principal Rajiv Ranjan, who subsequently referred it to the school's disciplinary committee. The two alleged assaulters were suspended for 10 days on the committee's recommendation but the order was withdrawn after the duo's guardians apologised in writing, even giving assurances that there would be no repeat of the offence.

The visiting team will submit its report to Upendra Kushwaha, Union minister of state for HRD, in a day or two. Reliable sources said the members were shocked at how the incident went unreported for so long.

"Such an incident can't be tolerated. It merits harsh punishment," a senior teacher of the school quoted the team members as saying.

Kushwaha ordered the inquiry as soon as he got to know of the viral video. On Friday, the minister said action will be taken against the school.

In the video, two boys who resemble the accused are seen in school uniform mercilessly beating up another student, who resembles the boy who has alleged he was beaten up, in a classroom in the presence of three other students. The victim's cries for help go unheeded.

The video was allegedly made by a friend of the two brothers and released on WhatsApp to terrorise other students.

But by Thursday evening it was all over the place after news channels picked it up.

The incident is said to be fallout of a complaint lodged by the attacked boy, a resident of Ramdalayu Nagar in Muzaffarpur, against the two brothers. "But the school authorities kept the matter under wraps for over a month and didn't inform the police," an investigating officer said.

Muzaffarpur district magistrate Dharmendra Singh said he received a letter from the school principal about the incident on Thursday.

"The letter was forwarded to the senior superintendent of police (SSP) for necessary action," he said, refusing to elaborate further.

On Muzaffarpur SSP Vivek Kumar's instructions, an FIR was lodged with the Kazimohammadpur police stations on Thursday night against the two brothers. The SSP said the brothers have been detained for interrogation and have been shown the video clip to substantiate the charge against them.

The SSP said the investigating officer has also been directed to initiate action against the school authorities for suppressing the incident.

"The statement of the victim has been recorded to verify the truth," he told The Telegraph.

"The FIR was lodged on the statement of school principal Rajiv Ranjan," Muzaffarpur deputy superintendent of police Ashish Anand said. "The police will send the video for forensic test to ascertain its authenticity. We will be able to say more about the case only after getting the report. In the meantime, the investigation will proceed."

The father of the accused boys, a Border Security Force deserter, faces charges of murder, loot and extortion in Muzaffarpur, West Champaran, East Champaran and Gopalganj districts. He was arrested and sent to jail in 2013.

The assaulted boy said he had been thrashed twice earlier. "I had verbally complained to the school authorities but nothing happened," he said.

The attacked boy's family has even shifted house, fearing reprisal from the henchmen of the jailed gangster.