Five Palestinian children were among 21 people killed in Israeli air strikes on Gaza early Thursday, medics said, with most of the bloodshed in the southern city of Khan Yunis.
The deaths bring to 72 the overall number of Gazans killed since Israel launched Operation Protective Edge early on Tuesday to halt cross-border rocket fire.
In the latest attack, a five-year-old boy was killed when an Israeli missile struck the northern Gaza town of Beit Lahiya, emergency services spokesman Ashraf al-Qudra told AFP.
The majority of deaths took place in Khan Yunis with a strike around 1:00am (2200 GMT) that hit a coffee shop where people were watching the World Cup semi-final match between Argentina and the Netherlands.
Eight people were killed and at least 15 wounded.
An hour later, Israeli warplanes struck two houses elsewhere in the city, killing four women and four children, Qudra said.
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Another raid targeted a house in Nusseirat refugee camp in central Gaza, killing one man.
Shortly after dawn, a missile hit a car in western Gaza City, killing three.
Separately, a man who was badly wounded in a raid east of Gaza City a day earlier died of his wounds, Qudra said.
His death raised Wednesday's toll to 30 people. On Tuesday, the first day of the operation, 21 people were killed.
The army said it had hit more than 300 targets overnight, raising the total number of strikes just over 48 hours to 750, in Israel's largest military operation in Gaza since November 2012.
There have been no Israeli deaths so far, but Hamas has launched waves of rockets across Israel that have triggered sirens in cities as far from Gaza as Tel Aviv, Jerusalem, and Haifa.