Israel Defense Forces soldiers killed 28 Palestinians across the West Bank and Gaza Strip on Wednesday. More than half of the fatalities were civilians killed by an errant IDF shell on the northern Gaza town of Beit Hanun.

Twenty-one Qassam rockets were fired toward Israel on Wednesday, Army Radio reported, after IDF artillery shells struck a residential area in Beit Hanun in the early hours of the day, killing 19 and wounding dozens of others.

At least ten of the rockets that followed the artillery round landed in the western Negev town of Sderot, including five fired over a one-hour span, between 9 A.M. and 10 A.M.

One rocket hit the commercial center of Sderot; another landed near the children's house in a Negev kibbutz. A Sderot woman was lightly hurt and 16 people suffered from shock, and a small fire broke out in the area of Kibbutz Zikim after a rocket landed there.

Israel was placed on high security alert following the shelling in Beit Hanun. Hamas swore to avenge the deaths, and called on all Palestinian groups to renew attacks inside Israel.

Later Wednesday, the head of Hamas' Qassam rocket unit, Ahmed Ouad, was killed along with another Hamas militant in an IAF strike on their car in the southern Gaza Strip.

Ouad is the son-in-law of Palestinian Foreign Minister Mahmoud Zahar of Hamas.

On Wednesday afternoon two Hamas militants were killed and four others wounded when the IDF opened fire on a Qassam rocket firing cell in northern Gaza. The dead were identified as Nimer Abu Al-Nadi, 17, and Iyad Swilan, 23.

Five other Palestinians, including four Al-Aqsa Martyrs' Brigade commanders, were killed in the West Bank, bringing the total number of people killed Wednesday to 28.

Palestinians hurled stones and Molotov cocktails Wednesday afternoon towards the Jewish area of Hebron following the strike. An IDF soldier was lightly wounded by a stone, and several Palestinians were wounded by rubber bullets. Students at Bir Zeit University in the West Bank city of Ramallah also protested and threw stones.

Eight children, seven women among dead in IDF shelling Eight children and seven women were among the dead, the Palestinain Health Ministry said, adding that 17 of the victims were members of the al-Ottomana family.

Khaled Radi, a Palestinian Health Ministry official, said all of those killed were civilians. According to witnesses, the victims were sleeping when the 15-minute barrage of shells first hit.

The victims were identified as Fatma Ahmed al-Ottomana, 80, Sanaa Ahmed al-Ottomana, 35, Naima Ahmed A al-Ottomana, 55, Masoud Abdullah al-Ottomana, 55, Sabah Mohammed al-Ottomana, 45, Samir Masoud al-Ottomana, 23, Fatma Masoud al-Ottomana, 16, Arafat Sa'ad al-Ottomana, 16, Mahdi Sa'ad al-Ottomana, 13, Mohammed Sa'ad al-Ottomana, 14, Sa'ad Majdi al-Ottomana, 8, Mahmoud Ahmed al-Ottomana, 13, Malik Samir al-Ottomana, 4, Maisa Ramzi al-Ottomana, 4, Nihad Mohammed al-Ottomana, 33, Mohammed Ramadan al-Ottomana, 28, Minal Mohammed al-Ottomana, 35, Saker Mohammed Adwan, 45, and Sa'adi Abu Amsha.

Radi also said at least 40 people were wounded, all civilians. Four hospitals are treating the wounded across Gaza. Two of the victims were evacuated to Tel Aviv's Ichilov Hospital with serious wounds to the heads.

Foreign Minister Tzipi Livni expressed regret for the deaths, saying that Israel did not set out to harm innocent civilians.

The IDF confirmed that an artillery battery containing 12 shells had aimed at a site from where Qassam rockets were fired at the southern city Ashkelon on Tuesday. The artillery fire had been intended for a location about half a kilometer from the Beit Hanun houses.

At this stage it is unclear whether the incident was caused by a technical or human error. Israel Defense Forces Chief of Staff Dan Halutz appointed Major General Meir Kalifi to head an investigation into the shelling.

Soon after the Wednesday attack, Peretz ordered the army to stop shelling in Gaza, and called for a speedy investigation into the incident. The army has reduced the amount of artillery fire into Gaza in recent months, saying it was ineffective against the Qassam cells and inaccurate. Nevertheless, the army decided to continue firing artillery shells sporadically, in specific instances.

At least seven houses in Beit Hanun houses were hit, witnesses said. "It is the saddest scene and images I have ever seen," 22-year-old Attaf Hamad said. "I saw people coming out of a house covered in blood. I started screaming to wake up the neighbors."

One man wailed as he tried to find his son. "Where is my son?" he screamed. "We were asleep and we were awakened by shells hitting the house of my uncle next door. Then the windows to our houses were blasted away," said Asma al-Ottomana, 14, who suffered shrapnel wounds. "We fled the house only to be hunted outside. The shells killed my mother and sister and wounded all my siblings."

Family member Akram al-Ottomana, an off-duty policeman, said he was woken at dawn by the sound of a shell exploding. "I looked, and about 50 meters away, I saw smoke coming out of the house of my uncle Saad," he said. "It looked like the shells hit the top floor, and my brother and I ran down into an alley."

He said he counted about 15 shells hitting and that many of the casualties were people who fled outside after the first explosions and were caught in the open.

"Projectiles were fired directly onto the people who were rushing out of the house," he said. "There was blood everywhere. I saw my neighbor, Sakher Adwan, he went to get his sister, and he was killed."

Rahwi Hamad, 75, who lives across the street, said he woke to the sound of shells exploding and people screaming.

"I opened my window and I looked out and I saw a shell hit a neighbor's house ... When I came out, another shell had hit the house," he said. "There was a stench of blood and (burned) flesh."

Large holes had been punched in the fronts of the houses and their balconies had collapsed. Surviving relatives sat weeping in front of the buildings. One man dipped his fingers in a puddle of blood and daubed it on his face. "God avenge us, God avenge us," he cried.

Firefighters hosed the blood off buildings and cobblestones while ambulance crews gathered body parts from nearby streets and gardens.

The incident comes a day after the IDF ended a week-long military assault in which at least 52 militants and civilians were killed.

Earlier Wednesday, an Israel Air Force air strike destroyed the house of a leading Hamas militant in Gaza City, Hamas and security sources said. No one was injured in the strike, they said, as the occupants were warned ahead of time to leave.

Four Al-Aqsa militants killed in West Bank In the West Bank, IDF troops ambushed a group of Palestinian militants near the West Bank town of Jenin early Wednesday, killing four, Palestinian security officials said.

After the ambush and the ensuing gunbattle, 30-year-old Ayman Kabala had climbed to his a rooftop to observe the clashes was shot dead, security and medical officials said.

The military said it was checking the report.

The four local commanders of the Al-Aqsa Martyrs' Brigade, a violent offshoot of Palestinian Authority Chairman Mahmoud Abbas' Fatah Party, were walking in the streets of Kfar Yamoun in the early morning when IDF troops opened fire, the security officials said.

The Al-Aqsa commanders were identified as Salim Abu Al-Hija, Mahmoud Abu Al-Hasan, Taher Abara and A'ala Hamaysa.

The troops and militants exchanged fire, and the men fled into a nearby olive grove, where other soldiers shot them dead, they said.