(AP) A surgeon who contracted Ebola in his native Sierra Leone died Monday while being treated in a biocontainment unit at a Nebraska hospital, the facility said.

Dr. Martin Salia died of the disease shortly after 4 a.m., Nebraska Medical Center spokesman Taylor Wilson said.

"Dr. Salia was extremely critical when he arrived here, and unfortunately, despite our best efforts, we weren't able to save him," said Dr. Phil Smith, medical director of the biocontainment unit.

Salia, 44, had advanced symptoms when he arrived at the hospital Saturday, including kidney and respiratory failure, the hospital said in a statement. He was placed on dialysis, a ventilator and given several medications to support his organ systems.

Salia was given the experimental drug ZMapp on Saturday. He also received a plasma transfusion from an Ebola survivor -- a treatment that is believed to provide antibodies to fight the virus.

The first two Ebola patients to return to the U.S., Dr. Kent Brantly and Nancy Writebol, were treated with ZMapp in August. Their treatments exhausted that supply of ZMapp and Salia was treated using a new batch of the drug.

"We used every possible treatment available to give Dr. Salia every possible opportunity for survival," Smith said. "As we have learned, early treatment with these patients is essential. In Dr. Salia's case, his disease was already extremely advanced by the time he came here for treatment."

Two other Ebola patients have been successfully treated at the Omaha hospital. Of 10 people to be treated for the disease in the United States, all but two have recovered. Thomas Eric Duncan, of Liberia, died at a Dallas hospital in October.

Salia's wife, Isatu Salia, said Monday that she and her family were grateful for the efforts made by her husband's medical team.

"We are so appreciate of the opportunity for my husband to be treated here and believe he was in the best place possible," Salia said.

Ebola has killed more than 5,000 people in West Africa, mostly in Liberia, Guinea and Sierra Leone. Five other doctors in Sierra Leone have contracted Ebola, and all have died.

Salia had been working as a general surgeon at Kissy United Methodist Hospital in the Sierra Leone capital of Freetown. It's not clear whether he was involved in the care of Ebola patients. Kissy is not an Ebola treatment unit, but Salia worked in at least three other facilities, United Methodist News said, citing health ministry sources.

Salia first showed Ebola symptoms on Nov. 6 but tested negative for the virus. He eventually tested positive on Nov. 10.