Eyewitnesses said the 50-odd goons entered the campus around 6.30 pm. The students' union tweeted that the attackers were "unknown ABVP goons" and were even beating up professors trying to protect students. JNUSU vice-president Saket Moon said, "The police have been in the campus since afternoon, but they have done nothing". Others pointed to the delay in calling in the police and their failure to make any arrest.

"The mob threw huge stones and entered hostels," a professor, Atul Sood, told NDTV. "These were not small stones, these were big stones that could have broken our skulls. I fell on the side and when I came out, I saw cars completely vandalised, including my car."

Condemning the violence, the University said Sunday's incident was linked to the agitation over a fee hike. Students opposing the hike wanted to disrupt the admissions process and there have been clashes and vandalism on Friday and Saturday. On Sunday, students against registration process beat up those in favour of it before the police could reach, the registrar said in a statement.

Late in the evening, senior police officer Devendra Arya said the situation in the university was normal. "We carried out an extensive flag march. The hostel areas have been secured. There is no report of violence," he said, adding that the police had entered the area on a written request from the university authorities.

The Congress's Priyanka Gandhi Vadra visited AIIMS where the injured students -- all from Left-backed groups -- were taken. Aishe Ghosh, the JNUSU president who was bleeding heavily when she was taken to hospital, was "singled out and hit on her head by men who entered the university campus with the blessing of the guards, the administration and the police," a tweet from JNUSU read.

The ABVP said their members were "brutally attacked by students affiliated to leftist student organizations SFI, AISA and DSF". "Around 25 students have been seriously injured in this attack and there is no information as to the whereabouts of 11 students. Many ABVP members are being attacked in hostels and the hostels are being vandalized by the leftist goons," the ABVP tweet read.

Foreign minister Dr S Jaishankar, an alumnus of the university, tweeted: "Have seen pictures of what is happening in #JNU. Condemn the violence unequivocally. This is completely against the tradition and culture of the university."

Activist Yogendra Yadav was manhandled thrice outside the university. "This is an attack right under the nose of Delhi police...this was an attack on the university," he told NDTV. He also claimed that he had information that the police had been present all along at the gates of the university, but did not act. "It is beyond shocking," he said.

Congress's Rahul Gandhi condemned the attack. "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," his tweet read.