Yes. When it comes to terrorism, it happens quite frequently. The Taliban constantly showed this with larger numbers. It's all 'cause most individuals involved are only told of the plan in the last moment. The same with the Russian invasion, soldiers coming out saying they didn't know they were going to war and so on. So you can imagine only about 100 people or so knew the plan and they led the invasion into Israel with the rest just doing as they are told.
Even if Israel knew it was coming, they wouldn't have allowed such a massive degradation of the frontline, they would have prepared for it with reserves at the very least. But, no, even important bases fell into their hands, the Hamas has even gained control over many armored vehicles. They would have prepared for those ridiculous gliders as well. Just 1 or 2 gunships would have done the trick.
You can see based on circumstantial evidence alone that Israel did not know the attack was coming.