World leaders have paid tribute to the victims of Saturday's plane crash in southern India that left 158 people dead. Chinese premier Wen Jiabao and Pakistani Prime Minister Yousuf Raza Gilani were among those offering condolences. The plane, arriving from Dubai, overshot Mangalore airport's hilltop runway and crashed down into a valley. Officials say an inquiry into the causes of the crash is under way. The plane's "black box" data recorders have yet to be found. All the passengers on the flight were Indian nationals, with many returning from jobs in the Gulf to visit their families. 'Difficult to bear' Mr Gilani, whose country often has tense relations with its neighbour, was quick to send a message to Delhi. "On behalf of the government and the people of Pakistan and on my own behalf, I would like to convey our deepest condolences and sympathies to the bereaved families," his statement said. Russian President Dmitry Medvedev and Bangladesh's Sheikh Hasina also sent messages of condolence. US ambassador to India, Timothy J Roemer, said his country was ready to provide assistance. "This is of course so much more difficult to bear knowing that so many children perished," he said. There were thought to be 20 children on board the Air India Express flight. On behalf of the UK, Foreign Secretary William Hague said his thoughts were with the victims and their families. Throughout India, prayers were offered and groups of people with ties to Karnataka state, where the accident happened, gathered to remember the victims. Buddhist monks in the central city of Bhopal lit candles at a prayer ceremony for the crash victims. Good safety record Mangalore's airport lies on top of a hill with steep drops at the end of each of its two runways. One of the runways was extended in 2006 to accommodate larger planes like the Boeing 737. Analysts say the position of Mangalore's runways poses challenges for pilots. But the secretary of India's Civil Aviation Ministry, M Madhavan Nambiar, told reporters some 32,000 landings had taken place on Mangalore's runway. Officials said it was too soon to speculate on the causes of the crash. India's air safety record has been good in the past decade, despite a rapid increase in the number of private airlines and air travel in the country. The last major crash happened in the city of Patna in July 2000, killing at least 50 people. Source: BBC