At an emergency meeting, meanwhile, the U.N. Security Council unanimously called the crisis "a threat to international peace and security" and urged all countries to provide experts, field hospitals and medical supplies. It was only the second time the council addressed a health emergency, the first being the AIDS epidemic.
And in Guinea, seven bodies were found after a team of Guinean health workers trying to educate people about Ebola was abducted by villagers armed with rocks and knives, the prime minister said. Among the dead were three Guinean radio journalists.
Many villagers in West Africa have reacted with fear and panic when outsiders have come to conduct awareness campaigns and have even attacked health clinics.
The disease, which has also touched Liberia, Nigeria and Senegal, is believed to have sickened more than 5,300 people and killed more than 2,600 of them, the U.N.'s World Health Organization reported. In a sign the crisis is picking up steam, more than 700 of those infections were recorded in the last week for which data is available.
During the lockdown in Sierra Leone, set to begin at midnight Thursday and run through Sunday, volunteers will try to identify sick people reluctant or unable to seek treatment. They will also hand out 1.5 million bars of soap and dispense information on how to prevent Ebola.
Authorities have said they expect to discover hundreds of new cases during the shutdown. Many of those infected have not sought treatment out of fear that hospitals are merely places people go to die. Others have been turned away by centers overwhelmed with patients.
Sierra Leone's government said it has prepared screening and treatment centers to accept the expected influx of patients after the shutdown.
"Today the life of every one is at stake, but we will get over this difficulty if all do what we have been asked to do." Sierra Leone's President Ernest Bai Koroma said in an address late Thursday.
As shoppers rushed to buy food and other items ahead of the deadline, some merchants worried about how they would feed their own families after losing three days' income. Much of Sierra Leone's population lives on $2 a day or less, and making ends meet is a day-to-day struggle.
"If we do not sell here we cannot eat," said Isatu Sesay, a vegetable seller in the capital. "We do not know how we will survive during the three-day shutdown."
The U.N. Security Council resolution was co-sponsored by an unprecedented 130 countries, reflecting the rising global concern.
"This is likely the greatest peacetime challenge that the United Nations and its agencies have ever faced," said Dr. Margaret Chan, WHO chief.
She added: "None of us experienced in containing outbreaks has ever seen, in our lifetimes, an emergency on this scale, with this degree of suffering, and with this magnitude of cascading consequences."
U.N. Secretary-General Ban Ki-moon called for a 20-fold increase in aid totaling almost $1 billion to deal with the crisis.
Several countries promised aid even before the resolution was adopted.
France announced Thursday it will set up a military hospital in Guinea in the coming days, while Britain said it will provide 500 more badly needed beds in Sierra Leone. The U.S. plans to send 3,000 military personnel to the region and build more than a dozen treatment centers in Liberia. An American general has arrived in the Liberian capital of Monrovia to set up a command center.
Ebola, which is spread through bodily fluids, puts health workers at a particularly high risk. Nearly 320 have become infected, and about half have died. A French nurse for Doctors Without Borders who became infected in Liberia was being flown to Paris on Thursday.
With no proven treatment for the disease, public health experts have kept the focus on isolating the sick, tracking down those they have come into contact with, and stopping the chain of transmission through travel restrictions, the cordoning off of entire communities and now Sierra Leone's lockdown.
Some patients have been given the blood of Ebola survivors in an experimental approach that some scientists think can help people fight off the virus.
British nurse William Pooley, who was infected while working in Sierra Leone and has since recovered, has flown to the U.S. to donate blood to an American patient.
Reached at his Atlanta hotel Thursday night, Pooley acknowledged he was there to donate blood to a patient at Emory University Hospital. But he - and hospital officials - declined to identify the patient or detail his condition.