At least 274 Palestinians were reportedly killed during the Israeli raid that rescued four hostages held by Hamas on Saturday, making it among the bloodiest assaults by Israel since the start of the latest Mideast war.
An initially lower figure was updated Sunday by the Gaza Health Ministry.
Israel acknowledged fewer than 100 Palestinian casualties but denied a Hamas claim that some hostages were killed during the daytime rescue operation and accompanying air assault on Nuseirat in central Gaza, Reuters reported.
"It's a blatant lie," Israeli military spokesperson Peter Lerner told CNN.
Another Israeli military spokesperson, Rear Adm. Daniel Hagari, said the raid took place in the heart of a residential neighborhood where the hostages were being held in two separate apartment blocks.
Israel troops came under heavy fire and responded "from the air and from the street," Hagari told reporters during a briefing.
"We know about under 100 [Palestinian] casualties. I don't know how many from them are terrorists," he said.
An Israeli special forces commander was killed during the operation, according to a police statement.
Palestinian paramedics and Nuseirat residents said the raid left the mangled bodies of men, women and children strewn around a marketplace and a mosque, and unconfirmed video footage posted on social media showed bodies with their entrails spilling onto bloody streets.
"It was like a horror movie but this was a real massacre. Israeli drones and warplanes fired all night randomly at people's houses and at people who tried to flee the area," said a paramedic and Nuseirat resident who identified himself as Ziad, 45.
The Hamas-run Gaza Health Ministry initially said as many as 100 Palestinians were killed, without saying how many were Hamas fighters.
The Hamas government media office later increased the death toll to at least 210, with many more wounded, but that figure couldn't immediately be confirmed, Reuters said.