Four people were removed from a Chicago-bound flight Tuesday morning after a passenger reported "suspicious" behavior as the plane taxied to the runway.

Spirit Airlines Flight 969 was leaving Baltimore-Washington International Thurgood Marshall Airport when "a passenger alerted a flight attendant of a passenger engaged in suspicious activity on board," airlines spokesman Stephen Schuler said.

Maryland Transportation Authority Police spokesman 1st Sgt. Jonathan Green told NBC Chicago the passenger saw another passenger "watching a media report at that time and that's what concerned her."

Green said the captain asked police to remove three men and a woman from the plane. Those people were interviewed and later released, he said.

Multiple passengers told NBC Chicago the people removed from the plane appeared to be of Middle Eastern descent.

Witnesses said the incident all started after a woman on the flight was seen running from her seat to the back of the plane.

"All of a sudden a woman got up when we were about to take off and she just ran, ran right to the back of the plane and the flight attendants were on the PA saying, 'Ma’am please slow down, you have to slow down,'" said passenger Jenna Farelli. "I started praying to God."

Shortly after, passengers said the pilot told them the flight was being escorted back to the terminal and law enforcement was going to come onto the plane.

"It was like the scariest moment of my life," said Farelli. "The plane stopped immediately and then they went to taxi us back and the pilot said that everyone remain calm, that you have to stay in your seat and law enforcement is going to be on the plane. Of course we’re all freaking out. It’s just super silent on the plane."

Officers then entered the plane, questioned three people and escorted them off the plane before coming back and asking one more passenger to leave, according to witnesses.

"There was no question at all, no talking at all, [the passengers] grabbed their bags and got off the plane," said passenger Spencer Padgett.

"The passengers that were called off certainly handled it well," said witness Tilesha Northern. "I would perceive it as something one could have gotten offended about."

All passengers were eventually deplaned after the incident.

"This basically was a see something, say something situation," Green said, adding that the flight's delay was "in the interest of public safety."

Once the Transportation Security Administration cleared the plane and luggage, the flight departed for Chicago's O'Hare International Airport after 9 a.m., according to Schuler. It had been scheduled to leave at 6 a.m.

"You just never know and I definitely don’t fault Spirit," said passenger Frank Sheffield. "I’m glad for the inconvenience. I’d rather be a little late. At least we got here."