Nineteen Palestinians, including 17 members of a single family, were killed by stray Israel Defense Forces artillery shells that hit a house in Beit Hanun, in the northern Gaza Strip, early yesterday morning.

About 40 Palestinians were wounded in the incident, most of them women and children. Two of the injured were sent to Israel for treatment.

Eight other Palestinians, including one civilian, were killed in other incidents in the territories yesterday.

In response to the Beit Hanun shelling, senior Hamas members called for a resumption of terror attacks inside Israel, while Khaled Meshal, the head of Hamas' political bureau, called a press conference in Damascus and said that a temporary halt in such attacks had come to an end. Islamic Jihad also vowed revenge attacks, as did the Fatah-affiliated Al-Aqsa Martyrs Brigades.

In response to these threats, the security services were placed on high alert yesterday. Israel security officials believe the terrorist organizations will try hard to carry out a major attack in the near future.

According to eyewitnesses, seven or eight shells landed on the four-story building that housed the Al-Ottamana family. Most of the family was still asleep at the time, and those who were not killed instantly by the first shell were hit by subsequent shells as they tried to flee.

Prime Minister Ehud Olmert and Defense Minister Amir Peretz published a joint statement in which they expressed regret for the civilian deaths and offered humanitarian assistance to the Palestinian Authority. Pursuant to this offer, Israel sent a large amount of medical supplies into Gaza.

Later, Olmert's political advisor, Shalom Turjeman, called PA Chairman Mahmoud Abbas' office to verbally express the prime minister's regret.

The IDF also appointed an inquiry committee, which is due to submit its findings to Peretz and IDF Chief of Staff Dan Halutz tonight, and Peretz ordered the IDF to freeze all artillery shelling of Gaza until the investigation had been completed.

But GOC Southern Command Major General Yoav Galant defended the shelling, saying: "Israel's citizens don't know how many times artillery fire has prevented Qassam [rocket] launches. When you fire at the launching area area two or three hours in advance, there is a good chance of preventing the Qassam fire."

Yesterday, Palestinians fired 14 Qassams into Israel.

According to Palestinian sources, the casualties of the shelling included
Fatma al-Ottomana; her son, Massoud Abdallah al-Ottomana, 55; his wife, Sabah Mohammed al-Ottomana, 45; and their children, Samir Massoud al-Ottomana, 23, and Fatma Massoud al-Ottomana, 16. Massoud's brother, Saad, and two of his children were injured, while his pregnant wife and three other children - Arafat, Mahdi and Mohammed - were all killed, as were two of his grandchildren, Saad and Mahmoud. At least two of the family's neighbors were also killed while trying to rescue the wounded from the building.

The IDF inquiry committee, headed by Major General Meir Kalifi, is examining two main options for what caused the disaster: a technical problem or human error. The problem (or error) could have occurred in either the artillery battery's radar or its firing computer, both of which are operated manually.

Based on the committee's findings to date, the course of events leading up to the incident is as follows:

At 4 P.M. on Tuesday, four new and improved Qassam rockets were fired at
Ashkelon from a copse north of Beit Hanun. No one was hurt.

Later that evening, the IDF obtained intelligence indicating that Hamas
intended to fire more of the new-model Qassams at Ashkelon yesterday morning, apparently from the same site - which was chosen because it is not visible from any IDF lookout post. The Gaza Division - which has in general sharply reduced its use of artillery fire since Brigadier General Moshe Tamir took command of it in August - therefore instructed the artillery battery stationed at Be'eri to be prepared to shell the site, in the hope that this would deter the Qassam launchers from going there.

The battery then made the usual preparations to adjust the range: It fired three or four shells at a site a few hundred meters away from the real target and used the battery's radar to find out where they had landed, after which it adjusted the guns' settings accordingly.

At about 5:30 A.M. yesterday morning, the battery fired 12 shells programmed to land about 1,200 meters from the houses of Beit Hanun. These shells hit the target and caused no casualties.

At 5:45 A.M., the battery fired another 12 shells, this time programmed to land about 450 meters from the houses. All were launched from a single barrel to increase the accuracy. According to the battery's radar, 10 shells hit the target, but the radar was unable to determine where the other two had landed. A few minutes later, the first reports of civilian casualties in Beit Hanun began arriving.

Unknown number of shells
The IDF is still not sure whether only the missing two shells hit the
al-Ottomana house, or whether there were more. Artillery gunners who saw
photographs of the damage on television said it looked as if a sizable number of shells had landed on it.

According to the IDF, the "normal" margin of error for an artillery shell
under these conditions is about 200 meters, which is why IDF regulations for Gaza state that artillery targets must be at least 200 to 300 meters from civilian houses. But a 450-meter deviation would require only a three-degree deviation in the gun barrel, which is "undetectable by the human eye," said Brigadier General (reserves) Zvi Fogel, a former senior artillery officer.

Fogel told Haaretz that there are two possible explanations for the error: a problem with the radar, which resulted in the gun's range being wrongly adjusted Tuesday evening, or a problem with the battery's computer, which wrongly implemented the correct range settings obtained from the radar.

Kalifi, who is heading the inquiry committee, also presided over the IDF's probe of a blast that killed several members of a Palestinian family on a beach near Beit Lahia last June. In that inquiry, Kalifi concluded that the blast was caused not by an IDF artillery shell, but by Hamas explosives planted near the site to foil a possible landing by naval commandos. The Palestinians completely rejected this conclusion.

In this case, however, IDF officers said there was no doubt that IDF shells were responsible; the only question is how the error happened.

Commentary: