Survivors of the crash described hearing a loud thud shortly after touchdown and said the main fuselage broke into two before filling with fire and thick smoke.
The investigation into the crash was called off in darkness on Saturday night.
Investigating teams resumed combing the wreckage on Sunday, and recovered the "black box" cockpit data recorder that they hope could shed light on the cause of the disaster.
A team from the US National Transportation Safety Board (NTSB) was to arrive in India to assist investigators.
Three officials from the NTSB, a US federal agency that investigates civil transportation accidents, will be joined by teams from the Federal Aviation Administration and Boeing, an NTSB spokesman told the German Press Agency DPA.
The team was to leave the US on Sunday evening and arrive in Mangalore by Tuesday morning.
Boeing said in a statement that it too was invited by Indian authorities to provide technical assistance to the investigators.
Officials described the landing conditions as fair with good visibility and said there had been no distress call from the cockpit.
Praful Patel, the Indian civil aviation minister, who flew to the crash site on Saturday, said: "The preliminary observation is that the aircraft touched down and did not contain itself within the runway space."
He described the chief pilot, a Serbian national, as a "very experienced" flier who had logged 10,000 hours of flying time.
Runway in focus
Stressing that it was "too early" to determine the precise cause of the crash, Patel acknowledged that the sanded safety area surrounding the runway in the event of an overshoot was shorter than at some airports.
"It does not have much of a spillover area [and], in this case, apparently it had not been able to stop the plane," he said.
Vasanthi Hariprakash, a reporter in Mangalore with India's NDTV channel, said investigations have begun at the crash site to determine what happened.
"What has been debated is the structure of the airport," she told Al Jazeera.
"The airport is about 40 years old [and] we are talking about a very difficult topography. The airport is surrounded by hills. [An accident] of this magnitude has raised questions of the flying ability and how much risk was involved.
"This particular airport is a little tricky because it does not have the required 100 yards just in case the plane veers off the runway. But those are questions that will be seriously probed in the days to come."
Television images from the immediate aftermath of the crash showed smoke billowing from the fuselage, as emergency crews, who struggled down steep, wooded slopes to reach the aircraft, sought to douse the fire with foam.
Overnight Air India released the names of seven survivors.
Air India Express is a budget airline operated as a subsidiary by the state-run carrier.
Saturday's disaster comes as Air India is struggling to turn around its finances after posting a net loss of more than $1bn last year.
The Mangalore tragedy is the first major air crash in India in nearly a decade.
Sixty-one people were killed when a Boeing 737 aircraft belonging to the domestic airline, Alliance Air, crashed into a residential area near the airport in the eastern Indian city of Patna in July 2000.