Israel steps up pressure on Hamas, killing 20

On Thursday, Israel carried out more than 10 airstrikes in northern and central Gaza, beginning just after midnight and stretching well into the afternoon, Palestinians said.

The army said it was targeting rocket squads, and blamed militants for operating in populated areas. Civilian casualties were unintended, the army said.

AP photos showed rockets being launched from densely populated areas in northern Gaza. At nightfall Thursday, Hamas said it had fired 82 rockets since Wednesday, including 51 at Sderot.

One missile strike killed two Palestinian brothers and their two cousins who were playing soccer in a field in the town of Jebaliya, their relatives said. A 12-year-old boy who was nearby later died of his wounds, medics said.

Later Thursday, a helicopter attacked a Hamas police post near the home of Haniyeh, the Hamas prime minister, in the Shati refugee camp. One person was killed and four people were wounded, officials said.

Another Israeli airstrike late Thursday hit an electric company vehicle in Khan Younis, killing two workmen, medics said. The Israeli military said they hit a car carrying militants.

Among the militants killed Thursday was Hamza al-Haya, the son of Hamas lawmaker Khalil al-Haya. The elder al-Haya, one of Hamas' top figures in Gaza, has escaped assassination attempts, including an Israeli strike that killed his brother last year.

Visiting the morgue Thursday, Khalil al-Haya said he was proud his son had lost his life. "This is the 10th member of my family to receive the honor of martyrdom," he said.

In Tokyo, visiting Israeli Prime Minister Ehud Olmert said Israel will go after the militants. "We will reach out for the terrorists and we will attack and we will try to stop them," he said.

Rice, who briefly met with Olmert in Tokyo, said Hamas rocket attacks "need to stop," but also expressed concern for the humanitarian situation in Gaza and urged calm on all sides.

Israel's public security minister, Avi Dichter, visited Sderot Thursday, but was forced to cut short a news conference when an air raid siren went off and his guards rushed him to a concrete shelter. Before Dichter arrived in the town, two people were hurt by rocket fire, including one of his bodyguards.

Dichter told reporters he had no quick solution for the rocket attacks, but rejected suggestions of opening a dialogue with Hamas, which Israel considers a terrorist group.

More from msnbc.com Joblessness spurs surge in disability claims Cosmic Log: ‘Ardi’ is science’s top 2009 breakthrough Rudolph, the dog, teaches kids lesson Air ambulances leave some with sky-high bills  Gift of giving takes on a whole new meaning   Al-Qaida leader’s wife calls women to join jihad Send your holiday pictures to troops

MORE FROM MIDEAST & N. AFRICA

Mideast & N. Africa Section Front

Pentagon: Insurgents intercepted spy videos Ship carrying dozens sinks off Lebanese coast Yemen: Up to 34 al-Qaida militants killed   Moms of US hikers in Iran left in dark about case Car bomb near central Baghdad restaurant kills 3 Mideast & N. Africa Section Front   Add Mideast & N. Africa headlines to your news reader: