The Israeli military is investigating the possibility that munitions stored near a compound in Gaza hit by an air strike on Sunday may have caught fire, killing more than 40 civilians, Reuters reports.

Chief military spokesperson Rear Admiral Daniel Hagari said it was still unclear what set off the deadly blaze in the southern Gaza city of Rafah, but added that the 17-kilogramme munitions used in the strike were believed to be too small to have set off such a big fire.

“We are looking into all possibilities, including the option that weapons stored in a compound next to our target which we did not know of may have ignited as a result of the strike,” he told a televised briefing, adding that footage of the incident indicated there were secondary explosions following the strike.