(Al Jazeera) – Umm Luay zooms in on a photograph on her mobile phone and kisses the screen, again and again. In the photo, her son, Luay Kaheel, is seen smiling alongside his friend, Amir al-Nimra. The two teenagers, 16 and 15 respectively, died on Saturday minutes after an Israeli air raid hit the rooftop of a building in Gaza where they were playing. “I heard an explosion, and instinctively knew that something had happened to my son,” Umm Luay, 33, told Al Jazeera on Sunday, surrounded by a group of women sitting inside her home in Gaza.