At least 15 people were killed and another 150 people wounded in an Israeli air strike on a market near Gaza City, medics said.
Emergency services spokesman Ashraf al-Qudra said the strike hit a busy market in the battered Shejaiya neighbourhood, which lies between Gaza City and the Israeli border.
The strike came shortly after the Israeli army said it was observing a humanitarian lull that would be in force for four hours from 1200 GMT.
But it said the lull would not apply in areas where troops were "currently operating" in a move denounced as a publicity stunt by Hamas.
GMT 14:30 2017 Thursday ,27 AprilTwo US troops killed fighting IS in Afghanistan
GMT 14:28 2017 Thursday ,27 AprilKenya opposition names Raila Odinga as presidential candidate
GMT 13:18 2017 Thursday ,27 AprilKremlin urges restraint after alleged Israeli strikes on Syria
GMT 12:58 2017 Thursday ,27 AprilEurozone recovery 'increasingly solid'
GMT 12:32 2017 Thursday ,27 AprilRussian navy ship sinks, crew rescued: Turkish coastguard
GMT 12:31 2017 Thursday ,27 AprilTurkey's AKP to hold extraordinary congress May 21
GMT 12:13 2017 Thursday ,27 AprilGerman inflation shoots up to 2.0% in April
GMT 12:11 2017 Thursday ,27 AprilRussian navy ship damaged in collision off Turkish coast