GAZA CITY, Gaza Strip - The Israeli army attacked a series of targets throughout the Gaza Strip on Wednesday, killing at least 19 Palestinians including a Reuters cameraman, medical officials said. Three Israeli soldiers died in separate fighting.

The bloodshed marked a sudden spike in violence in Gaza, which had experienced a relative lull since Israel ended a broad offensive in the area in early March. The Israeli army often operates in Gaza to prevent Palestinian militants from firing rockets into southern Israel.

In the deadliest incident, an Israeli helicopter fired four missiles at targets near the Bureij refugee camp in central Gaza. At least 11 Palestinians, including two youths, were killed, said Dr. Moaiya Hassanain of the Palestinian Health Ministry.

The Reuters cameraman, Fadal Shana, 23, apparently was killed along with two bystanders in an airstrike in the same area, according to his colleagues and medics.

Cameramen who rushed to the scene said they saw the Reuters jeep on fire, and Shana's body lying next to the jeep, alongside other casualties. They said Shana's jeep was marked as "press" and that the cameraman was wearing an identifying flak jacket.

As colleagues rushed toward Shana, another missile was fired, said Wissam Nassar, a photographer with the Maan news agency. "There was an airstrike. We were thrown back, myself and another person."

Reuters Editor-in-Chief David Schlesinger called for an investigation.

"This tragic incident shows the risks journalists take every day to report the news. All governments and organizations have a responsibility to take the utmost care to protect professionals trying to do their jobs," he said in comments posted on the company's website.

"Our thoughts are with his family. We request an immediate investigation into the incident by the Israeli defense forces."

The army confirmed a helicopter had targeted a group of gunmen in Bureij; it did not have any immediate comment on the cameraman's death.

Dozens of Palestinian journalists went to the hospital where Shana was pronounced dead to pay their respects. In all, four journalists have been killed covering the West Bank and Gaza Strip since 1992, according to the Committee to Protect Journalists.

In separate fighting, five Palestinian militants were killed, Palestinian officials said.

Also Wednesday, Palestinian militants ambushed an Israeli ground force in northern Gaza, killing three soldiers, the army said.

Israeli defense officials said the soldiers had entered Gaza in pursuit of two Hamas militants who planted a bomb near the border. The soldiers were then ambushed by another Hamas force lying in wait, Israeli defense officials said.

The attack occurred near the Nahal Oz terminal used by Israel to pump fuel into Gaza. The fuel supply was cut off last week after two Israeli civilians were killed in a Palestinian attack on the terminal -- the only source of fuel for Gaza. Hours after Wednesday's ambush, Israel resumed fuel shipments to Gaza, Israeli and Palestinian officials said.

Mahmoud Khuzandar, deputy director of the Gaza fuel station owners' association, said a total of eight truckloads of fuel were delivered. He said half was cooking oil, and the other half was diesel fuel for Gaza's only power plant.

The fuel deliveries were expected to provide minor relief to the Gaza Strip, though they were only a tiny fraction of what the impoverished territory needs, Khuzandar said.

Israel has been cutting back on fuel and other basic supplies allowed into Gaza for months, trying to pressure Gaza's Islamic Hamas government to stop rocket attacks.

Without adequate fuel in Gaza, the area's roads are mostly empty, and people rely on walking, bicycles and crammed shared taxis for transportation. Some vehicle owners in the territory have converted their cars to use cooking gas, and may be able to refuel in coming days. However, most Gazans still rely on gasoline and diesel to power their cars. Most residents are unable to pay soaring black market prices for scarce fuel supplies. On Tuesday, the United Nations said it was gravely concerned about the effects of the fuel cutbacks.

Wednesday's violence threatened to spark a new wave of fighting between Gaza militants and the Israeli army. Israel's latest offensive killed more than 120 Palestinians, including dozens of civilians. Since Israel ended the offensive, Egypt has unsuccessfully been trying to mediate a cease-fire.

Hamas is committed to Israel's destruction, while Israel considers Hamas a terrorist group.

Hamas violently seized control of Gaza last June from forces loyal to moderate Palestinian President Mahmoud Abbas. Its control of the area, along with the near-daily fighting with Israel, has jeopardized Mideast peace efforts.

Israel hopes to reach a peace agreement with Abbas's West Bank government by the end of the year. But it says it will not carry out any accord until Abbas regains control of Gaza.