Eight people have been rescued and rushed to local hospitals, an Air India official said. Rescue operation was hampered by the thick smoke that engulfed the plane, airport authorities said.
Referring to those on-board the aircraft, chief minister of Karnataka, B S Yediyurappa, said: "They're all not alive".
At least 160 passengers have died in the crash," V.S. Acharya, home minister of Karnataka, earlier told reporters. "At least five to six people have been taken to hospital, their condition is not known."
The crash occurred at 6:03am. The aircraft was on fire, an Air India spokesperson said. About 25 fire tenders and ambulances are on the spot, authorities said.
The incident happened near a valley 10 km from the airport, Karnataka home minister V S Acharya said.
The flight IX-812, operated by a Boeing 737-800, had 163 adult passengers, 4 infants and 6 crew members on board.
Aviation sources said the aircraft overshot the runway, hit the fence and went beyond the boundary wall of the airport.
It was not immediately clear what caused the crash, although Mangalore deputy police commissioner R. Ramesh said the airport had been lashed by heavy rains which had hampered rescue efforts.
Television footage suggested the plane had partially broken up, with smoke billowing from the main fuselage, as rescue workers sought to douse the fire with foam and pulled bodies from the wreckage.
"The plane had broken into two. I jumped out of the plane after it crashed. I saw two other people also come out," Abdullah, a survivor from the plane, told local channel TV9 from hospital. "There was tyre-burst kind of noise. I tried to get out of the front but saw that there was a big fire. So I went back again and jumped out from there."
One television channel showed a fireman carrying in his arms what seemed to be the remains of a child.
Charred bodies and an engine lay in the forested terrain. "The flight had already landed. There was slight rain. The flight skidded off," eyewitness Mohiuddin Bava told a channel. "After that it caught fire. Villagers, everyone there, came to rescue. The plane wings are right in front of me now."
Aviation sources termed it an 'accident' instead of 'incident', they said. In aviation parlance an accident denotes causalities.
AI has opened helpline centre at Delhi Airport and the two numbers are 011-2565-6196 and 011-2560-3101. Mangalore Helpline number is 0824-2220422.
Prime Minister Manmohan Singh has announced a compensation of Rs 2 lakh each for the families of those killed in Mangalore air crash and Rs 50,000 for the injured from the PM's National Relief Fund.
Meanwhile, civil aviation minister Praful Patel has rushed to the spot. Congress president Sonia Gandhi also expressed grief and sorrow over the tragic air accident in Mangalore. In a message, she wished speedy recovery to those injured.
DGCA Director-General S N A Zaidi said, "we have received only preliminary reports regarding the accident. But we are waiting for the details including the number of passengers."
India's worst aviation accident occurred in 1996 when two passenger planes collided in mid-air near New Delhi with the loss of all 349 on board both flights.
