An airline passenger who arrived at Newark International Airport in New Jersey on Tuesday is being evaluated for Ebola after he showed symptoms similar to the virus, including a fever, during an airport health screening. The man had flown into the U.S. on a United Airlines flight from Brussels but started his trip in Liberia, according to the New York Post. He was transferred to a New Jersey hospital, where health officials are monitoring his case.

"During the enhanced screening process for individuals arriving to the United States from Liberia, Sierra Leone and Guinea, an individual was identified as reporting symptoms or having a potential exposure to Ebola," Centers for Disease Control and Prevention spokesperson Carol Crawford said in a statement. Should health officials find a reason to suspect Ebola, they will contact the other passengers, Crawford said.

The hospital where the passenger from Liberia was taken, University Hospital, is one of the state’s three Level 1 trauma centers. The hospital has a contract with the city to take all medical cases from Newark Airport. Hospital staff told visitors Tuesday night that the facility was on “lockdown,” according to Yellow tape blocked the emergency room entrance and cars were not allowed to enter the hospital’s parking garage. "No one knows what's really happened,” a parking garage attendant told “No one knows if this is protocol…I just want to know what's going on. I just want to be safe.”

The passenger, a Liberian national, had waited in line at the customs check-in at Newark with the other passengers when health agents singled him out for a health screening because of his recent travel history. Agents found that the man had a fever, NBC New York reported. He has been isolated, although it is unknown whether he had any other symptoms.

Newark International Airport is one of five airports in the U.S. where health inspectors have been posted to screen travelers coming from the West African countries of Guinea, Liberia and Sierra Leone, where the Ebola outbreak has killed more than 4,500 people and infected thousands more. The screenings began earlier this month and involve taking passengers’ temperatures as they disembark and determining their travel history. “We work to continuously increase the safety of Americans,” CDC Director Tom Frieden said last week. “We believe these new measures will further protect the health of Americans, understanding that nothing we can do will get us to absolute zero risk until we end the Ebola epidemic in West Africa.”