I just read the entire original article at The Jewish Chronicle (linked below). It is an amazing story. The spies were not found out in advance of the operation. The commandos went to the third floor of the house after rescuing the hostages on the second floor and found 30 terrorists on the third floor. That's when the intense fighting broke out.
I cannot begin to imagine the incredible confusion of that battle. I like how the Israeli Air Force flattened the two homes as soon as the hostages and troops were evacuated.
The inside story of Israel’s dramatic Gaza hostage rescue