Forty years ago today, on June 23, 1985 (May 6, 1985), an Indian airliner exploded in mid-air, killing 329 people. On June 23, 1985, an Air India jumbo crashed into the Atlantic Ocean near Ireland, killing all 329 people on board. Indian officials said the crash was apparently caused by a bomb planted on the plane by a Sikh extremist group in retaliation for a 1984 attack by Indian troops on the sect's holy site, the Golden Temple. Air controllers at Hong Kong Airport said they had been in contact with the plane, which had flown from Toronto to Mumbai that morning via London, just eight minutes before it suddenly disappeared from radar screens. Air officials said the pilot did not mention any factors that could have caused the sudden crash. Even if all four of the Boeing 747's planes malfunctioned at the same time, there would be enough time to send a call for help. Because of a series of threats, Canada has stepped up security at civil aviation terminals in Toronto and Montreal, scanning and screening all baggage with X-rays. In a phone call to the newspaper, people claiming to represent the Sikh organization claimed responsibility for planting the bomb on board.