Videos that emerged after the assault late Sunday showed people in masks roaming inside the corridors of Jawaharlal Nehru University and beating students who were protesting against a fee hike.
Most of the injured were treated at a hospital for cuts and bruises, said Aarti Vij, a spokeswoman at the All India Institute of Medical Sciences.
New Delhi Police Commissioner Amulya Patnaik said the incident was a clash between rival student groups.
Opposition parties and injured students blamed the Akhil Bharatiya Vidyarthi Parishad, a student organization linked to Prime Minister Narendra Modi's Bharatiya Janata Party.
"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," tweeted Rahul Gandhi, a leading politician from the main opposition Congress party.
Akhil Bharatiya Vidyarthi Parishad, which includes students at Jawaharlal Nehru University, released a statement saying they didn't start Sunday's violence and insisted their members were attacked first by students with links to communist groups.
Communist-linked student organizations at the university have led recurring protests against the fee increase, which went into effect in November. Opponents say the fee hike makes education too expensive for many.
Surya Prakash, a 25-year-old research scholar at JNU's Sanskrit school, said Monday that he had been brutally beaten in the attack. He said he cried out to his attackers that he is blind, but the beating continued anyway.
"They first broke the door and windows of the room and barged inside and hit my head with a rod," Prakash said in his dorm room.
One floor up from Prakash, above the dorm warden's residence, students said two Kashmiri Muslim students living in adjacent rooms were targeted. While the attackers used a fire extinguisher to ram one door open, one student climbed over his balcony into the room next door while another jumped onto the ground below, sustaining an injury, according to Mukesh Kumar, a research scholar who lives across the hall.
An ambulance carrying injured people off campus was attacked by a group of men with sticks while police stood by, several bystanders told The Associated Press.
On Monday, the shattered window exposed a room in disarray, with shards of glass and wood and a fire extinguisher on the floor. Next door, the room was also littered with broken glass, a cup of tea and a cellphone left on the desk.
Students said the masked attackers also entered women's wings in the dorms.
Geeta Thatra, a 32-year-old history student, described the incident, saying she could see people wearing masks enter the dorms and scream "beat them up."
The AP accessed an audio clip recorded by a student during the attack in which the assailants could be heard shouting while they run amok smashing windows and asking the fear-stricken students to open the doors of their rooms where some of them had hid to escape the violence.
Expressing fear, Thatra accused the administration of giving "free rein" to the attackers.
"We saw the brutal vandalizing at the Jamia university. There they used police to do it and here they have used other forces, the so called mobs, to do it," she said, referring to the December violence in which police barged inside Jamia Millia Islamia university in New Delhi, tear-gassing students and beating them up.
"It is impossible for the students to enter without the complicity of the administration," Thatra said.
The government was quick to condemn the violence.
"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," Finance Minister Nirmala Sitharaman, a member of the prime minister's party, said on Twitter.
The party itself released a statement blaming opposition parties for the violence and trying to "create unrest to shore up their shrinking political footprint."
Amnesty International said the attack is "not an isolated incident and must be seen amidst the larger pattern of pushback as massive protests continue unabated across the country."
Hours after the attack, students across the country took to the streets to protest the incident.
Hundreds of students and ordinary people of the city gathered outside police headquarters in New Delhi and accused officers of inaction.
In Mumbai, students from several educational institutions gathered at the Gateway of India and demanded that the government act against the assailants.
Students at a university in Uttar Pradesh state held a candlelight march to protest the incident.
The violence comes amid simmering anger over the government's new citizenship law, which has resulted in a series of violent protests and clashes around the country that have left at least two dozen people dead.