KUALA LUMPUR: Police have arrested an 11-year-old and six teenagers in connection with the fatal tahfiz school fire that killed 21 students and two wardens at the Darul Quran Ittifaqiyah Tahfiz Centre on Thursday. City police chief Commissioner Datuk Amar Singh said that the suspects aged between 11 and 18 years old were behind the attack on the school and that they are investigating the case as mischief by fire and murder. He said the case will be investigated under Section 435 of the Penal Code for mischief by fire and Section 302 for murder. "The seven suspects were arrested on Friday ... The motive of the fire was due to 'mocking' between some of the tahfiz students and the suspects," he said. He also added that six of them had tested positive for use of marijuana when they were arrested on Friday. However, he did not say which of the suspects tested negative for the substance. "Based on CCTV footage we obtained from the PPIM building nearby and our investigations, we managed to catch the seven youths who where behind the attack," he said at a press conference today. He said that two of the suspects had previous criminal records one for rioting and another for theft of a vehicle. "The suspects were school students and school leavers who were from the Keramat area," he said. Amar added that investigations found two gas cylinders were moved from the first floor of the school to the upper floor. He also said that an accelerant was used. Police had also seized clothes, helmets and a motorcycle from the suspects. He also added that these seven suspects will be remanded for seven days until Sept 22. "With the arrests of the seven suspects, we consider the case solved, this is a tragedy and I am happy we can solve it and can bring peace to the families," he said. The 5.15am fire at the tahfiz school resulted in the death of 21 students and two teachers. Six other students sustained injuries.