Firefighters respond to medical emergency at airport. (Sarah McCarty / AL.com)

BIRMINGHAM, Alabama -- A patient who got sick on a plane that landed on Thursday afternoon in Birmingham is not believed to be at risk for the Ebola virus, according to Birmingham health and fire officials.

The passenger got sick on a United Airlines flight and was suffering from nausea and vomiting, Birmingham Fire and Rescue Service Battalion Chief C.W. Mardis said. After the passenger's history was evaluated by Jefferson County Public Health Officer Dr. Mark Wilson, it was determined that he was not at risk of having the Ebola virus.

Birmingham firefighters arrived in hazardous material protective gear and set up a command post after a passenger on-board a flight that arrived at the Shuttlesworth-International Airport showed "signs of symptoms of Ebola." Assistant Chief Tim Love said the fire department wanted to take no chances after a recent Ebola death in Texas.

All passengers and crew were told to remain on the plane, but they have now been released. The airport is back to normal operations.

The flight, operated by ExpressJet, originated in Chicago and landed at Birmingham-Shuttlesworth International Airport around 3:24 p.m. There were 40 passengers on the plane. The flight was supposed to land in Birmingham; it wasn't rerouted.

The passenger was taken to UAB Hospital, and Mardis said it isn't clear what exactly the illness was.

"Symptoms are same as many other things, in other words they are non-specific: Fever, nausea, headaches which can range from the flu to any number of illnesses," Dr. Mary McIntyre, Alabama state epidemiologist, said.

Mardis emphasized that the hazmat response was out of an abundance of caution. Birmingham Fire and Rescue worked on procedures for possible Ebola infections about a month ago, he said, after the epidemic in West Africa and the infections of Americans made headlines. But, Mardis said, what might be Ebola could be anything.

"The flu is 'Ebola-like symptoms,'" he said.

Jeremy Gray, Carol Robinson and Mike Oliver contributed to this report.