Thousands of Palestinians turned out Friday for the funeral of 21 people who died in a Gaza Strip apartment building fire, an AFP correspondent said. At least seven children were among the dead in the blaze at Jabalia Palestinian refugee camp on Thursday night, said the head of the Indonesian Hospital there, Saleh Abu Lai. Mourners carried the coffins, draped in Palestinian flags, through crowds in the camp toward Beit Lahia cemetery for burial. While the cause of the fire remained unknown, a spokesman for the civil defence unit told AFP that supplies of fuel were stored in the three-storey building. Jabalia is a refugee camp, but like many such Palestinians camps now includes large buildings and in many respects resembles a city. With electricity supply sparse in the impoverished territory, domestic blazes are common, as Gazans seek alternative sources for cooking and light, including kerosene lamps. Gaza, densely populated with 2.3 million people, has been under Israeli blockade since 2007 when the Islamist movement Hamas took power. Israeli Defence Minister Benny Gantz tweeted that his staff would assist with “humanitarian evacuations of the injured to (Israeli) hospitals”. He expressed sympathy for the “serious disaster” in Gaza. It was not immediately clear, however, if any of the roughly 15 people injured in the fire were transported out of Gaza. Palestinian president Mahmud Abbas, based in the Israeli-occupied West Bank — a separate Palestinian territory — considered the fire “a national tragedy”, his spokesman said. In May last year a war between Hamas militants and Israel killed 260 in the territory, Gaza authorities said, and left 13 people dead in Israel, the police and army there said. Israel and another Iran-backed militant group, Islamic Jihad, fought a three-day conflict in Gaza in August this year.