Twelve people were killed on Sunday afternoon when a rocket hit a gathering spot in Kfar Giladi in the Upper Galilee.
Ten people died on the spot, and an eleventh person died of his wounds shortly after he was taken to hospital. Another person died in the evening, raising the death toll to 12.
Eleven of the 12 victims were identified early Monday morning as: Eliyahu Elkariaf, 34, of Granot; Yosef Karkash, 41, from Afula; Shlomo Buchris, 36, of Sde Yitzhak; Yehuda Greenfeld, 27, from Ma'ale Michmash; Ziv Balali, 28, from Kfar Saba; Daniel Ben David, 38, from Ahitub; Marion Berkovitch, 31 of Ashdod; Ro'I Yaish, 27, from Herzliya; Shaul Shai Michlovitch, 21, from Netanya; Shmuel Halfon, 41, of Bat Yam; and Gregory Aharonov, 34, from Or Akiva.
In addition, twelve people were wounded in the attack.
MDA said that those who were badly hurt were treated on location, and were airlifted to hospitals in the region.
"It was a direct hit on a crowd of people," Dan Ronen, the chief of the northern police command, told Army Radio.
Convoys of police and rescue vehicles raced to the town.
"This was the most difficult thing I could have imagined in my career. There are nine bodies here covered in blankets, around us cars are going up in flames," Army Radio reporter reported as she choked back tears. "On one side is the cemetery, on the other side are the nine young bodies waiting for burial."
A security official said it was the "worst attack" that Israel sustained since hostilities broke out 26 days ago.
"The scene is very difficult it can be described as a battlefield," said Shimon Abutbul, a rescue worker who was one of the first to arrive in the area. "There was a lot of blood."
"We saw difficult scenes in the days of this fighting. This is the worst I have seen," he said, adding that the rocket hit cars among other things in the area.
A nearby forest burst into flames from the barrage and huge plumes of gray smoke rose into the air.
Many of the rockets hit the nearby town of Kiryat Shmona, damaging a synagogue and sparking a series of fires, Mayor Haim Barbivai said, calling on all residents to remain in their shelters because more barrages were sure to follow.
Rockets also landed in Haifa and the surrounding bay area, Nahariya, Karmiel, Rosh Pina, the Golan Heights, Ma'alot and Safed.
This latest barrages of rockets follows a weekend in which three people were killed
when a rocket scored a direct hit at their home in a western Galilee Arab-Israeli town.
The three were a 60-year-old woman and her two daughters, both in their 30s. They were all in the same room at the time of the strike.
They were later identified as Fadya Juma, 60, and her daughters Samira, 33, and Sultana, 31.
Some 170 rockets landed in Israel throughout Saturday, with 120-130 of those falling in one hour in the late afternoon.