Ra’anana, Israel — We were awoken at 6:30 a.m. on Saturday — the Sabbath, as well as the Jewish holiday of Simchat Torah — by the all-too-familiar blare of the air-raid siren. Dutifully entering the bomb shelter in our house, we assumed the alert was a mistake, as it sometimes is. Little did we realize our country’s nightmare was only beginning.

Under cover of a massive rocket barrage — more than 2,000 projectiles in less than an hour — Hamas, the genocidal terror group running the Gaza Strip, breached the border wall and dispatched hundreds of fighters to the small Israeli communities near the coastal enclave. Over the course of the next several hours, the highly trained Hamas militants slaughtered more than 800 Israelis, wounded another 2,500, and took more than 100 hostage — almost all of them civilians.

If this description sounds overly clinical, it’s a reflection of the careful planning, the premeditation, the deliberate nature of these unprovoked crimes against humanity carried out by the terrorist group. This was no heat-of-the-moment eruption of rage but a meticulously designed battle plan intended to murder as many defenseless Jews as possible. Hamas terrorists methodically went house to house, hunting the vulnerable and butchering those they didn’t have time or space to kidnap and take back with them to Gaza. This wasn’t some sort of cry for help: It was pure evil.

Many here in Israel have likened Saturday’s devastating events to September 11, and indeed, parallels abound. Like the U.S. on that horrific day, Israel was surprised by the brazenness of the assault and the diligence behind it (in Israel’s case, the attack arrived 50 years and one day after the shocking outbreak of the Yom Kippur War, which has been called Israel’s Pearl Harbor). Like the U.S., Israel faces an implacable enemy irrevocably dedicated to eradicating those who adopt a different way of life. And like the U.S., Israel will have to respond in a powerful and effective way to neutralize its vicious enemy.

But for Israelis, Hamas’s attack was much worse.

First, we suffered many more deaths Saturday, proportionally speaking, than al-Qaeda inflicted on 9/11: more than eight times as many, per capita. In such a small country, these heinous murders hit closer to home. Last night, we learned that a cousin and the son of friends are still unaccounted for after Hamas attacked their music festival, and earlier today, we received the tragic news that the sons of other friends fell in battle while trying to ward off terrorists. Our daughter, whose seminary sits a few miles from Gaza, reported that a friend hid all day in her bomb shelter and only by grace of God survived the onslaught. Israel, on its best days, and even its worst, feels like a large, unruly family, and we all lost relatives on Saturday.

Second, the sheer cruelty of the killings and abductions outside of Gaza carried a different resonance than the antiseptic piloting of planes into the Twin Towers, the Pentagon, and rural Pennsylvania. The Hamas terrorists looked into the eyes of the civilians they shot and killed. In videos they proudly published on social media, they exulted in their bloodthirsty orgy. These barbarous savages confidently paraded their terrified hostages around the streets of Gaza while supporters cheered lustily. One widely circulated photo depicted an 85-year-old grandmother taken captive; their depravity knows no bounds. On 9/11, we heard chilling recordings of cellphone conversations between frightened passengers unsure of what was going on; on Saturday, we heard calls and read texts from women and children whose homes were about to be breached by their murderers. The killings, the kidnappings, and the other acts of brutalization felt so much more visceral.

And finally, in planning its response, Israel is very likely to suffer heavy losses — even more severe, proportionally speaking, than those the U.S. absorbed in Afghanistan. A massive deployment of active-duty forces to Gaza, coupled with a far-reaching call-up of reservists, has touched every family in the country, where military service is obligatory. Our own son is guarding an outpost in an area that may become a flash point, and his friends — our friends’ children — are heading directly into the line of fire. Rescuing the dozens of women, children, and elderly Israelis held captive by Hamas will almost certainly necessitate a ground incursion into Gaza, and the further casualties inflicted on Israel will surely be immense. The Israeli family will lose more relatives as the days and weeks press on.

To be clear, none of this diminishes the unspeakable horror of September 11 or the memory of those who fell. In fact, just a month ago, this past 9/11, I paid my respects at the Pentagon memorial and thought back to that horrific day when my wife and I were living in Boston and realized our lives would never be the same. Little could we have known we would one day feel even worse. May God protect us all.