A humanitarian crisis turned deadly for the second time in a week, with six African immigrants killed Thursday in clashes with Moroccan police during a rush on the border between Morocco and this Spanish enclave by hundreds of men desperate to reach Europe.

Spain said it will start sending the Africans back, beginning with a boatload of 70 Malians. The boat was to leave for Morocco Thursday night, according to Deputy Prime Minister Maria Teresa Fernandez de la Vega.

Citing Abdellah Bendhiba, the governor of Morocco's Nador province, Morocco's MAP news agency said the Africans were killed early Thursday during an assault by 400 immigrants on guard posts in a forest overlooking Melilla. The Spanish enclave is the cherished destination of hundreds of Africans who have staged five such rushes over the past week.

Security services responded in self-defense, the report said, adding that 290 people were arrested.

"During this assault, the clandestines displayed exceptional violence, obliging the security services to respond in the framework of legitimate defense," the agency quoted Bendhiba as saying. "Unfortunately, six of the assailants died."

A government official in the Moroccan capital, Rabat, said police opened fire as the men rushed the fence, killing some of them, while others suffocated as they were trampled in the stampede. The official, who spoke on condition of anonymity because he was not authorized to speak publicly, did not provide a breakdown on the number killed by gunfire.

The Moroccan guard posts are located in the Gourougou forest — dense pines on a hill that overlooks Melilla — at a point known as Rostrogordo, where the 7.5-mile-long metallic border is about 6 1/2 feet high. The barrier is about 13 feet high elsewhere.

Many would-be immigrants spend months living in forests on the Moroccan side waiting to cross over. Rostrogordo is about nine miles from Melilla.

Morocco's communications minister, Nabil Benabdellah, said illegal immigration "is a delicate question that needs wise and rigorous treatment."

Morocco is a "victim" in the matter, he said, referring to the use of Moroccan soil by African immigrants hoping to make their way to Spain. He underscored the need for an approach that implicates Morocco's neighbors as well as the European Union, but did not specify a solution his North African nation would find acceptable.

On Sept. 29, five people died of gunshot wounds when a crowd of some 600 Africans tried to climb fences and reach another Spanish enclave, Ceuta, about 300 miles to the west, also on Morocco's northern coast. Two bodies were found on the Spanish side and three on the Moroccan side.

The deaths have intensified a crisis that has been brewing since August, when frenzied rushes on the Melilla and Ceuta borders began. The volume of men involved magnified dramatically with six huge rushes over the past week and hundreds of men scaling razor wire fences to reach the small outposts of Europe.

Spain announced plans to expel the Africans as it struggles to cope with an overflowing holding facility housing 1,600 immigrants in Melilla and the seemingly nonstop drive by immigrants bound to reach Spain.

Spain says it is acting under a never-enforced 1992 agreement with Morocco that lets it send back immigrants arriving from that country even if they are not Moroccan.

Under current Spanish law, the government lets African immigrants stay if they are from countries that do not have automatic repatriation agreements allowing Spain to send them back home. Most of the recent arrivals come from destitute sub-Saharan countries that lack such accords and refuse to take the people back.

On Thursday afternoon, as word of the planned expulsions spread through the hot, dusty camp, Africans held there expressed horror over the prospect of going back to Morocco. Many say they endured months of hunger, cold and beatings by Moroccan police while living in forests overlooking the Melilla border and waiting to try to cross over into Spain.

That suffering came after sometimes years-long trips from their destitute home countries. By making it into Melilla, they thought they were at last safe and had a chance of reaching the Spanish mainland and their dream of Europe.

"We thought we were at the end of our journey. It was nothing but happiness," said Jean Calvin, a 22-year-old man from Cameroon who took three years to travel to Morocco and then spent two more living in the bush. "Now, suddenly, everything has changed. Words escape me."

Luis Aghea, 25 and also from Cameroon, said this of the Spanish authorities: "If they saw where we were living, they would not send us back."

"I'd prefer to die here," he said.