UPDATE 3:15 P.M.:  A second person in Dallas, Texas, is displaying Ebola-like symptoms after coming into contact with Thomas Eric Duncan, the first person to be diagnosed with Ebola in the United States, who died earlier this morning.

The person is being transported to the hospital. Officials plan to give further details at a news conference later this afternoon.

Stay with Fox News for updates.

Duncan, 42, had developed symptoms of Ebola after returning from Liberia, where he was in contact with a woman who was infected with the deadly virus.

He was in serious condition last week, but was downgraded to critical condition over the weekend. Duncan had reportedly been receiving an experimental antiviral drug called brincidofovir.

"It is with profound sadness and heartfelt disappointment that we must inform you of the death of Thomas Eric Duncan this morning at 7:51 am. Mr. Duncan succumbed to an insidious disease, Ebola. He fought courageously in this battle. Our professionals, the doctors and nurses in the unit, as well as the entire Texas Health Presbyterian Hospital Dallas community, are also grieving his passing. We have offered the family our support and condolences at this difficult time," the hospital announced in a statement.

The Texas Department of State Health Services released the following statement:

“The past week has been an enormous test of our health system, but for one family it has been far more personal. Today they lost a dear member of their family. They have our sincere condolences, and we are keeping them in our thoughts. The doctors, nurses and staff at Presbyterian provided excellent and compassionate care, but Ebola is a disease that attacks the body in many ways. We’ll continue every effort to contain the spread of the virus and protect people from this threat.”

Secretary of State John Kerry addressed the Ebola threat this morning at the State Department just after news broke about of Duncan's death.

He called on more nations to join the international effort to combat Ebola, saying "not enough" are contributing.

"Some smaller countries are contributing way above their per capita population compared to other countries. But the fact is more countries can and must step up in order to make their contributions felt," said Kerry.

Read more below from FoxNews.com:

A hospital in Nebraska said it is using the same drug to treat an American journalist who was airlifted from Liberia and arrived Monday.

He had been in critical condition and on a ventilator and a kidney dialysis before his death.

Duncan had been in isolation since Sept. 28.

Authorities in the United States and the public are on alert following Duncan's diagnosis more than a week ago, which raised concerns that the worst epidemic of Ebola on record could spread from three hardest-hit impoverished countries - Guinea, Sierra Leone and Liberia. Duncan, who arrived in Texas in late September on a commercial flight from Liberia, has been in critical condition since Saturday.

Texas state health officials said they are monitoring 10 people who had close contact with Duncan and 38 others who came into contact with that group to see if anyone had developed signs of infection. So far, no one has shown any symptoms, health officials said.

Stay with Fox News for more on this developing story.