A plane carrying 190 passengers has crashed in monsoonal conditions in southern India, overshooting the hilltop runway and falling into a valley before breaking in two.

At least 18 people are believed dead and 123 injured, 16 of them seriously, as rescuers scrambled to find survivors in the mangled wreckage at the base of a slope.

The two-year-old Boeing 737-800 flying for Air India Express airline was repatriating Indian nationals who had been stranded abroad due to international COVID-19 travel restrictions.

Regular commercial flights have been halted in India because of the global coronavirus outbreak.

The pandemic repatriation flight crashed on landing in Kozhikode, in the state of Kerala, and was reportedly hampered by heavy rain and cloud which affected conditions and visibility.

Authorities have confirmed the rescue operation has been completed and two teams of investigators deployed to determine what happened.

The Air India Express plan overshot the runway while trying to land. Photo: Getty

Amitabh Kant, who heads the government’s planning commission, said the runway is on a hilltop with deep gorges on either side, making it difficult to land.

“The incident happened because of heavy rains and poor visibility. This is truly devastating,” he told NDTV.

The plane had flown from from Dubai to Kozhikode, also called Calicut, in India’s southernmost state, carrying a planeload of Indians returning home amid the pandemic.

Prime Minister Narendra Modi tweeted that he was “pained by the plane accident in Kozhikode,” and that he had spoken to Kerala’s top elected official.

Pained by the plane accident in Kozhikode. My thoughts are with those who lost their loved ones. May the injured recover at the earliest. Spoke to Kerala CM @vijayanpinarayi Ji regarding the situation. Authorities are at the spot, providing all assistance to the affected.

— Narendra Modi (@narendramodi) August 7, 2020

Civil Aviation Minister Hardeep S. Puri said the plane “overshot the runway in rainy conditions and went down 10.6 meters into a slope before breaking up into two pieces.”

Abdul Karim, a senior Kerala state police officer, said the dead included one of the pilots, that at least 15 of the injured were in critical condition, and that rescue operations were over.

Health workers transfer an injured passenger on a stretcher to a hospital in Kozhikode, Kerala. Photo: Getty

An inquiry will be conducted by the ministry’s Aircraft Accident Investigation Bureau, he said.

Dubai-based aviation consultant Mark Martin said that while it was too early to determine the cause of the crash, annual monsoon conditions appeared to be a factor.

“Low visibility, wet runway, low cloud base, all leading to very poor braking action is what looks like led to where we are at the moment with this crash,” Mr Martin said, calling for the European Aviation Safety Agency and the U.S. Federal Aviation Administration to assist with the Indian government’s investigation.

The plane broke in two after crashing into a valley. Photo: Getty

There were 174 adult passengers, 10 infants, two pilots and four cabin crew on board the aircraft.

Air India Express is a subsidiary of Air India.

-with AAP