At least six students are dead and dozens more are feared trapped beneath mountains of rubble after a five-story hostel building suddenly collapsed near a major university in India.

The terrifying disaster unfolded around 1:30 p.m. Sunday, Sept. 6, in New Delhi’s Satya Niketan neighborhood, close to Delhi University’s south campus.

Officials believe as many as 50 people may have been inside the aging building when it came crashing down.

Many of those staying there were students.

Rescue crews raced to the scene as frantic efforts began to reach people buried beneath concrete and twisted debris.

Authorities said at least six people had been killed, while three others were reported to be in critical condition.

Around eight people had been pulled alive from the wreckage as of Sunday, but officials feared another 30 to 40 could still be trapped.

In one especially chilling development, a local lawmaker told the BBC that some students trapped beneath the rubble had reportedly been able to make phone calls from inside.

“The exact number of persons trapped/injured is still not known at present,” officials said. “Further details will be shared as and when confirmed.”

Teams from India’s National Disaster Response Force, police and multiple fire departments descended on the cramped neighborhood and began digging through the debris.

Police told India Today that construction work had reportedly been taking place in the building’s basement when the structure collapsed.

Authorities have not yet determined whether that work played a role in the disaster.

The building, reportedly known as Hostel Daze, contained about 15 rooms, with roughly two or three students staying in each room. A medical shop was operating on the ground floor.

Because the collapse happened on a Sunday, when students had no classes, officials fear many residents may have been inside their rooms when the building gave way.

Delhi Chief Minister Rekha Gupta said a neighboring building was evacuated as a precaution.

“Every possible effort is being made to safely rescue those trapped,” Gupta said, according to the BBC.

The collapse also forced nearby colleges to take emergency action.

Motilal Nehru College and several other Delhi University schools announced that classes would be canceled Monday, Sept. 7.

Motilal Nehru College also opened its facilities to students who were displaced by the disaster, offering temporary shelter and food.

“Students who have been displaced or are unable to access their accommodation are requested to reach out and seek shelter at the college premises,” the school said on social media.

Police said they have identified the owner of the collapsed building and were attempting to locate him.

Gupta said authorities would take action following the tragedy, although investigators had not yet announced an official cause.

The National Students’ Union of India also demanded a full investigation and called for anyone responsible to be held accountable.

“Negligence with the safety of students and common people will not be tolerated at any cost,” the group said.

Building collapses have been a recurring problem in parts of India, particularly during the country’s monsoon season, which runs from roughly June through September.

Heavy and prolonged rainfall can further weaken older or poorly maintained structures.

For families waiting for news in New Delhi, however, the focus remained on the desperate search beneath the rubble as rescue workers continued racing to find survivors.