GAZA CITY, Gaza Strip &

Israeli aircraft struck a series of targets throughout the Gaza Strip today, killing 14 Palestinians &

including four youths &

in a fresh upsurge in fighting that threatened to provoke even harsher Israeli action.

The Israeli attacks stepped up the pressure on Hamas, a day after a rocket fired by the Islamic militant group from Gaza killed an Israeli man. One helicopter attack struck a target outside the home of Hamas Prime Minister Ismail Haniyeh.

However, Palestinian rocket fire continued throughout the day, lightly wounding two people and in one case, forcing a top Israeli security official to scurry for cover. Police said two rockets reached Ashkelon, a major city about 12 miles north of Gaza.

Today's violence raised the death toll in two days of fighting to 25 Palestinians and threatened to worsen the ongoing bloodshed in the area, which involves near-daily Palestinian rocket attacks from Gaza and harsh Israeli reprisals. Seven children were among the dead, according to Palestinian officials.

The latest wave of violence began on Wednesday when an Israeli air strike killed five Hamas militants traveling in a van. Israeli officials said that among the five were an unstated number who received weapons and explosives training in Iran, and local media reports quoted anonymous officials as saying the men were planning a large attack against Israel.

Hamas retaliated by firing more than 40 rockets into Israel, one of the heaviest barrages in months. One rocket landed on an Israeli college campus in the southern town of Sderot, killing a 47-year-old father of four. It was the first fatal rocket attack since last May.

Today, Israel carried out at least 10 airstrikes in northern and central Gaza, Palestinians said. The army said it was targeting rocket-launching areas. The army said it was targeting "militants and rocket-launcher squads."

Officials said 14 people were killed today. Five of the dead were civilians, including four boys who were struck as they played soccer in Jebaliya in northern Gaza. Relatives said the boys ranged in age from 8 to 14.

Ahmed Dardouna, a family member, said the boys were all related &

two were brothers and the others were their cousins.

"They were playing soccer east of the town, not far from our houses," said Dardouna, 42. He said distraught family members located the bodies at a hospital after the boys failed to come home.

Later today, a helicopter attacked a police roadblock about 150 yards from the home of Haniyeh, Hamas' prime minister, in the Shati refugee camp in Gaza City. One person was killed and four people were wounded, officials said.

The attack appeared to be a message to Hamas, since the area is not used to fire rockets. Haniyeh, who has been hiding from the Israelis for weeks, wasn't believed to be in the area.

In a statement earlier today, Haniyeh said Israel's ongoing attacks would "not weaken the steadfastness and the determination of the Palestinian people."

The Israeli army has U.S.-made F-16 warplanes and Apache helicopters, as well as locally developed pilotless drones, in its arsenal. Palestinian witnesses said all three types of aircraft were used in the recent attacks. The army did not immediately comment.

"We will reach out for the terrorists and we will attack and we will try to stop them," Israeli Prime Minister Ehud Olmert told a press conference in Tokyo, where he is winding up an official visit.

He also rejected calls to loosen an economic embargo on Gaza. The blockade has come under growing international criticism because of the hardship it has caused in Gaza.

"The only requirement we have of the Palestinians is stop killing innocent Israelis like they did last night," he said. "It's hard to do business when you have to bury your population as the result of the atrocities and the terror committed by the Palestinians."

Despite the Israeli attacks, Palestinian militants fired at least 10 homemade rockets into Israel, police said. Two people were lightly wounded, including a bodyguard of Public Security Minister Avi Dichter.

Dichter was not in Sderot at the time. But after he arrived, Dichter was forced to cut short a news conference when an air-raid siren went off and his guards rushed him into a concrete shelter.

Police said four foreign-made Katyusha rockets reached Ashkelon, a city of 109,000. Although there were no casualties, one rocket went through the roof of a crowded apartment building.

Israel has long feared that Ashkelon could soon face regular rocket attacks. Casualties have been kept relatively low because the rockets mostly land in sparsely populated areas next to the border.

In Gaza, Hamza al-Haya, the son of hardline Hamas lawmaker Khalil al-Haya, was among those killed today, Hamas said. The group said he had commanded a rocket-launching squad in northern Gaza.

Khalil al-Haya is one of Hamas' top figures in Gaza, and has himself escaped assassination attempts, including an Israeli strike that killed his brother last year.

Visiting the morgue at Gaza City's Shifa hospital today, Khalil al-Haya said he was proud that his son had lost his life for the Hamas cause, like many of his relatives.

"I thank God for this gift," he said. "This is the 10th member of my family to receive the honor of martyrdom." Several thousands people joined the funeral procession.

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

"We have to remember that the Hamas activities there are responsible for what has happened in Gaza &

the illegal coup that they led against the legitimate institutions of the Palestinian Authority," she Rice told reporters after the meeting. "It is very clear where this started."

Hamas violently seized control of Gaza last year from the forces of Palestinian President Mahmoud Abbas. Israel has been holding peace talks with Abbas' government in the West Bank, while battling Hamas in Gaza.

Rice is expected to visit the Middle East next week to help push peace efforts forward. Abbas and Olmert hope to reach a peace agreement by the end of the year, though both sides have warned that the target may be too ambitious.