NAVI MUMBAI, March 6 -- A 13-year-old boy died and 11 other children were injured after a portion of a building slab collapsed onto a ground-floor tuition class in Kopar Khairane on Thursday evening. Civic officials said the accident occurred between 4.30 pm and 5 pm at flat number 2 on the ground floor of Vidyabhavan Apartment in Sector 2, where teacher Shyamali Choudhary (53) was conducting a private tuition class for local children. Choudhary sustained minor injuries and was discharged after primary treatment. According to Navi Mumbai Municipal Corporation (NMMC), 11 students were present inside the flat when a section of the slab from the upper floor suddenly gave way and crashed down. "Fire brigade teams and disaster response personnel immediately reached the spot and rescued all the children trapped under the debris. The injured were shifted to nearby hospitals for treatment," an NMMC official said....