WARNING: This video contains distressing images and audio. Israeli strikes killed 17 people, Palestinian authorities said, in a Gaza market as a TV crew was filming a crowd gathered near an ambulance. The area of Shujai'iya has seen some of the heaviest bombardment since Israeli forces began an offensive with the declared aim of curbing rocket fire by Hamas militants. Residents say shells and two missiles hit the area as a crowd gathered to observe a fire at a petrol station. In the footage people can be seen and heard lying on the ground and praying as a succession of blasts cover the area in debris