Violence broke out at Jawaharlal Nehru University on Sunday night as masked men armed with sticks and rods attacked students and teachers and damaged property on the campus, prompting the administration to call in police which conducted a flag march.
At least 28 people, including JNU Students' Union president Aishe Ghosh, were injured as chaos reigned on the campus for nearly two hours.
Eyewitnesses alleged the attackers entered the premises when a meeting was being held by JNU Teachers' Association on the issue of violence on campus and assaulted students and professors.
They also barged into three hostels.
Video footage aired by some TV channels showed a group of men, who were brandishing hockey sticks and rods, moving around a building.
The Left-controlled Jawaharlal Nehru University Students' Union and the Rashtriya Swayamsevak Sangh-backed Akhil Bharatiya Vidyarthi Parishad blamed each other for the incident.
The violence at the university, whose students have been actively supporting the stir against the amended Citizenship Act, triggered a political furore with opposition parties accusing "those in power" of trying to scuttle the voice of students, while protests broke out near Delhi Police headquarters and at the Aligarh Muslim University against the incident.
Union human resource development minister Ramesh Pokhriyal Nishank condemned the violence and appealed for peace on the campus.
A ministry official said anarchy will not be tolerated and a report has been sought from JNU administration on the incident.
Senior Union ministers and JNU alumni S Jaishankar and Nirmala Sitharaman too condemned the violence.
Sitharaman said the pictures of violence were horrifying and asserted that the government wants universities to be safe spaces for all students.
Union home minister Amit Shah spoke to Delhi Police chief Amulya Patnaik and the ministry has sought a report from him.
Sources said the violence started around 5 pm near Sabarmati tea point in the campus, where there had been minor clashes over the issue of semester registration under the revised rules.
The JNU administration said "masked miscreants armed with sticks were roaming around, damaging property and attacking people" and that police had been called in to maintain law and order. "
"This is an urgent message for the entire JNU community that there is a law and order situation on the campus.... The JNU Administration has called the police to maintain order," JNU registrar Pramod Kumar said in a statement.
Late in the night, the university said a police complaint will be filed and violators of university rules and those trying to disrupt peaceful academic atmosphere of campus will not be spared. It also claimed that those who opposed the registration process started the violence in which several guards were also injured.
WATCH: Masked miscreants armed with stick attack JNU students
Amid allegations of delayed action, Delhi Police said it conducted a flag march and the situation was brought under control after it got a written request from the JNU administration to enter the campus. It, however, did not say if any arrests had been made.
There was a massive deployment of security personnel in and around the campus after the violence and the entrance gates were closed.
The students' union alleged its members, including Ghosh, were injured in stone pelting by ABVP members.
The JNUSU claimed "ABVP members wearing masks were moving around on the campus with lathis, rods and hammers".
"They are pelting bricks...getting into hostels and beating up students. Several teachers have also been beaten up."
But Akhil Bharatiya Vidyarthi Parishad alleged its members were brutally attacked by Left-affiliated student outfits, the Students' Federation of India, the All India Students Association and the Democratic Students' Federation, and 25 of them were injured, while 11 were missing.
Among the injured was the secretary of its JNU unit, it said.
Narrating the sequence of events, R Mahalaxmi, a professor of History department, said, "We had organised a peace meet at the tea point at 5 pm. As soon as it got over, we saw that a large number of people entered the campus and they started arbitrarily attacking teachers and students."
"How did such a large number of people with rods in their hands enter the campus, that is what we are wondering about. I think they were political activist instigated by the people who always call us anti-nationals," Pradeep Shinde, another professor, said.
The attackers stormed Sabarmati, Periyar and Koyna hostels.
Students said there were clashes between student groups outside Periyar hostel.
In a video shared online, Ghosh could be seen bleeding from the head. "I have been brutally beaten up by people wearing masks... I was there with one of my activists when I was brutally beaten up. I am not even able to talk," the student leader is heard saying in the clip.
The Congress termed the violence a "state-sponsored mayhem".
Expressing shock over the incident, Congress leader Rahul Gandhi said, "The fascists in control of our nation, are afraid of the voices of our brave students. Today's violence in JNU is a reflection of that fear."
Congress general secretary Priyanka Gandhi Vadra visited All India Institute of Medical Sciences, where 25 injured were undergoing treatment.
Some of the injured were also at Safdarjung Hospital.
"Now Modi-Shah's goons are rampaging through our universities, spreading fear among our children, who should be preparing for a better future... To add insult to injury, BJP leaders are all over the media pretending that it wasn't their goons who unleashed this violence. The people are not deceived," she tweeted later.
Swaraj Abhiyan chief Yogendra Yadav, who was allegedly manhandled outside the university, claimed no one was there to stop the "hooliganism" and he was not allowed to speak to the media.
Delhi Chief Minister and AAP convener Arvind Kejriwal tweeted, "I am so shocked to know about the violence at JNU. Students attacked brutally. Police should immediately stop violence and restore peace. How will the country progress if our students will not be safe inside univ campus?" Kejriwal said he also spoke to the L-G over the issue.
Delhi Lieutenant Governor Anil Baijal condemned the violence and said the situation was being "closely monitored".
"The violence in JNU against students and teachers is highly condemnable. Directed @DelhiPolice to take all possible steps in coordination with JNU Administration to maintain law and order & take action against the perpetrators of violence. The situation is being closely monitored," he tweeted.
Communist Party of India-Marxist general secretary Sitaram Yechury blamed the ABVP for the violence and alleged that the attacks were "planned" by those in power.
"It is a planned attack by those in power, which is afraid of the resistance provided by JNU to its Hindutva agenda," he tweeted.
A large section of JNU students have been taking part in the protests against the amended Citizenship Act in the national capital.
The university was earlier embroiled in a major row over alleged anti-national slogans being raised by some students in February 2016.
An HRD ministry official said, "We have sought an immediate report from the JNU registrar about the situation on the campus.We have spoken to the vice chancellor and Delhi police officials to ensure that peace is maintained on the campus."
"Horrifying images from JNU - the place I know & remember was one for fierce debates & opinions but never violence. I unequivocally condemn the events of today. This govt, regardless of what has been said the past few weeks, wants universities to be safe spaces for all students," Sitharaman tweeted.
Condemning the violence unequivocally, external affairs minister Jaishankar tweeted "this is completely against the tradition and culture of the university".