New Delhi CNN  — 

The only survivor of a helicopter crash that killed 13 people including India’s top military official is on life support, officials said Thursday, as the nation mourned the victims and investigations into the incident continued.

Group Capt. Varun Singh is in a “critical but stable” condition, according to the Indian Air Force (IAF).

Indian Air Force Group Capt. Varun Singh is in a "critical but stable" condition.

“Every effort is being made to save him,” Defense Minister Rajnath Singh told India’s Parliament Thursday before the legislature observed a moment of silence for the victims.

Group Capt. Singh is being treated at the Military Hospital in the town of Wellington in the southern state of Tamil Nadu, where the helicopter crash took place Wednesday.

India’s Chief of Defense Staff Gen. Bipin Rawat, his wife Madhulika Rawat, and 11 other military personnel died in the incident.

The Indian Air Force (IAF) helicopter that crashed was a Soviet-designed Mi-17V-5. It took off from Sulur Airbase at 11:48 a.m. local time and was due to land in the town of Wellington at 12:15 p.m. At 12:08 p.m., air traffic control lost communication with the aircraft.

Defense Minister Singh, who is not related to the captain, told Parliament locals noticed a forest fire in the town of Coonoor.

“(They) rushed to the spot where they observed the wreckage of a military helicopter engulfed in flames,” he said. “Rescue teams from the local administration in the vicinity reached the site and attempted to recover the survivors.”

The cause of the crash is not yet known and the IAF has ordered a tri-service inquiry – a high level special force command – into the incident. The flight data recorder was recovered from the crash site, the IAF said Thursday.

Gen. Rawat’s remains were scheduled to arrive in India’s capital, New Delhi, on Thursday. His family will pay their respects before his cremation on Friday with full military honors, according to the Indian Army.

The general’s home state of Uttarakhand, in northern India, announced a three-day mourning period on Wednesday.

The last rites for all the other deceased military personnel will also be given appropriate military honors, Rajnath Singh said.

Gen. Bipin Rawat speaks at a news conference in New Delhi on January 12, 2018.

Gen. Rawat was appointed India’s Chief of Defense Staff in December 2019 and was the first to hold the post. Prior to that, he served as the Chief of Army Staff for close to three years.

During a career spanning more than 40 years, Rawat commanded several battalions for the Indian Army and received several awards for his service.

A statement released by the Indian Army described Gen. Rawat as “a visionary who initiated far reaching reforms in the Indian military’s higher defense organization” and his wife as “an epitome of grace whose presence will be missed by everyone.”

Condolences for the bereaved families have been pouring in since Wednesday, with Indian politicians and foreign officials offering messages of support.

“We’ll remember Gen. Rawat as an exceptional leader who served his country and contributed to the U.S.-India defense relationship,” US Secretary of State Antony Blinken wrote on Twitter.

Indian Prime Minister Narendra Modi also tweeted of his deep anguish.

“Gen Bipin Rawat was an outstanding soldier. A true patriot, he greatly contributed to modernising our armed forces and security apparatus,” he wrote. “His passing away has saddened me deeply.”

Former Indian Army Chief Gen. Ved Malik called the tragedy a “loss for the nation.”

“Bipin had impeccable soldierly qualities, military knowledge & experience,” he wrote on Twitter. “Determined, articulate & straightforward in pursuing what he believed in.”