FREETOWN, Sierra Leone (AP) — Thousands of health workers began knocking on doors across Sierra Leone on Friday in search of hidden Ebola cases as the entire West African nation was locked down in their homes in an unprecedented effort to combat the deadly disease.

Authorities hope to find and isolate Ebola patients who have resisted going to health centers, often seen only as places to die. Some international health experts have warned that such a strategy could backfire especially if there are not enough beds at treatment centers for all the new patients found during the three-day lockdown which began Friday.

UNICEF said the measure provides an opportunity to tell people how to protect themselves.

"If people don't have access to the right information, we need to bring life-saving messages to them, where they live, at their doorsteps," said Roeland Monasch, UNICEF Representative in Sierra Leone. In a statement, the U.N. children's fund said the operation needs to be carried out "in a sensitive and respectful manner."

During this first-ever Ebola outbreak in West Africans, some people have lashed out at health workers, accusing them of bringing the dreaded disease. Others don't believe it exists. Many villagers have reacted with fear and panic when outsiders have come to conduct awareness campaigns, and this week such an encounter resulted in deaths.

Six people have been arrested in the killings of eight people in Guinea who had been on an Ebola awareness campaign there, the Guinean government said Friday. The team, accompanied by journalists, had gone to the village of Womey on Tuesday. Another team dispatched to look for nine missing members discovered eight bodies, including those of three local journalists, a hospital administrator and several health officials, the government said.

Only one of the missing, the son of a Womey deputy administrative leader, was found alive, hiding in the area, the government statement said.

In an address to the nation late Thursday, Sierra Leone President Ernest Bai Koroma said health workers would be handing out soap and that once a house had been visited it would be marked with a sticker. He urged Sierra Leoneans to abide by the order.

"The survival and dignity of each and every Sierra Leonean is at stake; all what we have toiled for as a people is at stake; this is a fight for each and every one of us; this is a fight for this land that we love," he said.

More than 2,600 people have died across West Africa, with more than half the fatalities recorded in Liberia.

Earlier this week, President Barack Obama pledged 3,000 troops and the first increased American military aid arrived in Liberia on Thursday, according to the U.S. Embassy there.

The C-17 U.S. military aircraft brought a team of seven military personnel along with some equipment on Thursday. An embassy statement said more supplies and personnel are expected in the coming days.

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Associated Press writer Jonathan Paye-Layleh in Monrovia, Liberia, and Boubacar Diallo in Conakry, Guinea, contributed to this report.