Kuala Lumpur - Malaysian authorities said Friday they had not ruled out foul play in a fire that killed 23 children and teachers in a religious school, as calls mounted for better safety regulations in Islamic study centres.The fire broke out in the boarding school in downtown Kuala Lumpur before dawn on Thursday. Firefighters extinguished the blaze within an hour, but not before it had gutted the school's top-floor dormitory.Rescuers found the bodies of 21 schoolboys and two teachers in piles, indicating there may have been a stampede as the students sought to escape the inferno.The fire and rescue department initially said they believed the blaze - the worst in Malaysia for two decades - was caused by an electrical short circuit or a mosquito-repelling device.But Khirudin Drahman, director of Kuala Lumpur's fire and rescue department, told AFP that authorities were now investigating claims gas cylinders could have played a role.One of the survivors said two cylinders were left by the dormitory door and had caught fire, preventing those inside from leaving."We have not ruled out foul play," Khirudin said, adding that fires in dormitories were typically caused by unattended cooking or mosquito coils."The forensic team is doing the laboratory tests. We want to wrap up the results as soon as possible."Horrific accounts emerged of students crying out in desperation and sticking their hands through the metal security bars surrounding the dormitory as the fire took hold, with neighbours looking on helplessly.Some managed to escape by breaking through a grille and jumping out or sliding down drain pipes. A handful are being treated in hospital.