Anti-terror officers were called to the incident just days after the Paris attacks which killed 130 people.
The alarmed passenger said she became worried when a man made several phone calls in another language and claimed she saw him receive a text message reading “BLR Dynamite” – apparently referring to an Bengaluru airport, India.
She said the man was travelling with two others and talking with a fourth.
The worried passenger notified crew who took the Spirt Airlines plane back to its gate at Baltimore-Washington International Airport and ordered all passengers off the plane while a woman and three men were detained for questioning.
Passengers said the group appears to be of Middle Eastern descent and security officials who went onboard said there was a “credible security threat”.
The four passengers were interviewed by Transportation Authority Police officers but no trace of the text message was found on the suspect’s phone.
Maryland Transportation Authority Police spokesman Jonathan Green said the passenger who had been talking on the phone allowed officers to check the device, and no text message with the word “dynamite” was found.
They were interviewed by Transportation Authority Police officers, an air marshal with the Transportation Security Administration and an agent with the Joint Terrorism Task Force but were released without charge a few hours later.
It transpired the suspect was just watching his news on his phone as he waited for he flight to depart for Chicago.
Despite the false alarm, Spirit Airlines refused to apologise for removing the passengers.
A spokesman for the airline said: “We do not tolerate discrimination or remove passengers because of where they are from, their ethnicity, or their religion.
“The passenger in question was removed from the flight because of his behaviour, which was breaking airline and FAA rules during the taxiing process, and refusing to cooperate with crew instructions.
“Law Enforcement was called and they chose to remove others who were traveling with the passenger who was breaking the rules.”
Mr Green added: “One of the three males was sitting next to a female passenger and apparently he was watching a media report. I don’t know of what nature it was, but given current events, I can imagine what it was.
“Being in her shoes, I’m guessing that combined with what she saw or heard created some concerns for her.
“She told the flight crew, which was most likely a flight attendant, and they spoke to the captain and the captain made the choice to go back to the terminal.
“We did not find any criminal activity or violations of any kind and they were free to do what they pleased at that point.”
Express