Kumar (57), who was appointed coach of TFA in 1996, complained of uneasiness at around 3.30 AM. When he was taken to Tata Main Hospital, the doctors declared him brought dead, Choudhari said.
He left behind his wife and a daughter.
Kumar represented India in SAF games at Kolkata in 1987, Pre-World Cup qualifying match at Abu Dhabi in 1990.
Kumar hogged the limelight after he scored a brace in an exhibition match against Bochum team of West Germany at Jamshedpur in 1986.
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He played for Mohammedan Sporting, Kolkata, between 1986 and 1990 and captained the side in 1989.
After completing AFC 'C' and 'B' coaching courses in 1997 and 2004, he finished the 'A' course in 2009.
A pall of gloom descended among the sports fraternity as large number of sportspersons including former and present footballers visited the hospital to pay their tribute.
Kumar's body will be brought to TFA campus tomorrow afternoon before his last journey to Parvati crematorium.