NEW DELHI — Dozens of masked men wielding sticks and iron rods attacked students and professors at one of India's most prestigious universities late Sunday, injuring more than 30 and heightening concerns about law and order in the world's largest democracy.

Ten eyewitnesses said the group entered Jawaharlal Nehru University in New Delhi and shouted a slogan used by India’s ruling right-wing Hindu nationalist party as they roamed the campus beating students, smashing windows and destroying property.

The incident comes at a moment of high political tension in India, where hundreds of thousands of people — including many students — have participated in protests against a controversial citizenship law passed last month. The law creates an expedited path to citizenship for non-Muslim migrants from three countries, a move that critics say is discriminatory and unconstitutional.

The violence at the university was not directly connected to the citizenship law but was rooted in a separate dispute roiling the campus over fees that also pitted student supporters of the government against its opponents.

The accounts of masked men roaming a well-known campus as students cowered in their dormitories and police officers posted at the main gate failed to intervene are inflaming concerns about how Indian authorities treat those they consider adversaries.

Last month, police stormed another university campus in the capital where a protest against the citizenship law turned violent, beating unarmed students and firing tear gas into a library. One student was blinded in one eye. In the state of Uttar Pradesh, police deployed lethal force to put down protests against the citizenship law, leaving at least 19 dead, vandalizing homes and arresting scores of people, most of them Muslims.

On Monday, fresh demonstrations against the previous day’s campus violence in Delhi took place in at least 19 cities across the country. Some protesters called for the resignation of Amit Shah, India’s powerful home affairs minister who also oversees law enforcement in the nation’s capital.

On Sunday night, several eyewitnesses said police officers stood by as a mob armed with sticks, iron rods and cricket bats entered the campus of Jawaharlal Nehru University, an influential bastion of left-leaning politics.

The mob yelled “Long live Mother India!” and attacked a meeting led by professors near a main crossroad on campus, hurling rocks at participants, witnesses said. The assailants then smashed through the glass gate at one dormitory, shouting, “We will spare no one today!” Panicked students sent SOS messages to their professors, asking where to hide.

Inside the dorm, Surya Prakash, a visually impaired doctoral candidate in Sanskrit, was sitting at his desk studying. Masked men broke into his ground-floor room and began to beat him with iron rods on his back and arms, he said.

“I pleaded with them that I am blind,” Prakash recalled. “One hit me even harder. There is terror in our hearts.”

Students said the masked attackers included members of the Akhil Bharatiya Vidyarthi Parishad, or ABVP, the student wing of the ruling Bharatiya Janata Party. Jyoti Kumari, a master’s degree student who filmed some of the violence at the dorm, said she recognized at least five ABVP members in the mob. The ABVP denied the allegation and blamed the violence on “communist goons.”

A senior Delhi police official, Devender Arya, told the television station NDTV that the police responded promptly to calls for help from the university administration and that authorities have begun working to identify the attackers. Arya did not respond to queries about eyewitness accounts of police inaction and allegations that police had also beaten students.

The incident sparked widespread criticism across India’s political spectrum. External Affairs Minister S. Jaishankar — an alumnus of the university — wrote on Twitter that he condemned the violence “unequivocally” and that it “was completely against the culture and tradition of the university.”

Members of the opposition Congress party said the brazenness of the attack and the lack of an immediate police response indicated it had some kind of official sanction. “It is an act of impunity and can only happen with the support of the government,” wrote P. Chidambaram, a senior Congress leader.

An official at the All India Institute of Medical Sciences, a nearby hospital, said that 36 people were admitted with injuries from the incident and that all were discharged by Monday afternoon.

Kumari Neelu, who is married to a professor at the university, said she had just stepped outside her home on campus when she saw the approaching mob. As she tried to film them, the men began to run toward her. She fled inside and locked the main door. The mob banged on her door with sticks and rang the bell nonstop. Her husband, Bikramaditya Choudhary, began calling the administration, security officers and the police.

“Nobody responded,” he said. “If the media hadn’t arrived, we may have been butchered.”

Eyewitnesses also alleged that the police not only failed to stop the violence but also beat up students. Vipul Vivek, a master’s degree student in philosophy, watched from behind shrubbery as the violence unfolded. After the mob left, he said, about 30 policemen arrived and beat the students holed up inside the dormitory that was earlier attacked by the mob. He ran toward a forested area and hid for 45 minutes.

“We can’t fight back against the police,” he said.

Tensions also spiked outside the main gate of the university. Hundreds of government supporters assembled and began to shout right-wing slogans in an apparent endorsement of the attack on students.

“Identify the traitors and shoot the bastards!” they yelled. “Get out of India!” At least three journalists were attacked by the same government supporters as they tried to film them.

Amrita Johri, a civil rights activist, said she saw the crowd vandalize an incoming ambulance. “Men whose faces were covered starting hitting and threatening us,” she said. “The police did not intervene even as people pleaded for help.”

 Tania Dutta contributed to this report.