Calcutta, May 14 :    Calcutta, May 14:  A 15-year-old girl died during a routine early morning swim in the Hedua waters on Tuesday, leaving in her wake a trail of unanswered questions. The body of Puja Jalan - fished out after more than three hours of the tragedy - had apparently 'not taken in any water'. Neither the Burtolla police nor the National Swimming Association (NSA), in charge of the swimming sessions, would venture beyond saying that Puja could have died of a stroke or a sudden cramp. 'We can't say what led to Puja's death till we get the post-mortem report,' said inspector S. Majumdar of Burtolla police station and investigating officer D.K. Kundu. NSA general secretary Sanat Ghosh echoed their view. Puja, a Class IX student of Welland Gouldsmith School in Bowbazar, had been swimming in the north Calcutta pool for the past four years. She was accompanied by her sisters (Payel and Sonu) and cousin (Shagun) to Hedua on Tuesday. None of them could, however, throw any light on the mysterious death - the first, according to the Association, in recent memory. The NSA was established in 1924 with around 4,000 members. Puja was the eldest daughter in the Jalan family living at 20, Sahitya Parishad Street. Like almost all summer mornings, Puja - accompanied by her sisters and cousin - left home for the last time, just before 5 am on Tuesday. The 5 am to 6 am slot is reserved for women at Hedua and the three girls - except young Sonu - lost no time in jumping into the pool, measuring 120 m in length and 50 m in width. They kept swimming till 6 am, when Payel and Shagun stepped out of the pool. 'We thought Puja must have left the water before us,' Payel later said. With no sign of Puja, the girls asked some NSA officials to look for their sister. Shagun left for the Jalan residence, less than a kilometre away, to alert the family. The NSA officials, meanwhile, contacted the police for divers and pressed some of their expert swimmers into service. Puja's body was finally recovered around 9.45 am, from a point in the pool about 15-feet deep. Medical College and Hospital pronounced her 'brought dead'. Puja's family and friends alleged that there were not enough trainers at the Hedua pool on Tuesday morning. Her uncle, Sajjan Jalan, and her father's friend, Vikram Kothari, said the NSA management did not have the requisite number of trainers for so many swimmers. Ghosh, however, refuted the allegations, saying the club employed 15 trainers for every shift. 'Puja was a fairly good and experienced swimmer and the trainers were there to attend to the beginners,' he added.