Authorities in Florida say three men detained Friday for more than 17 hours may have been part of a hoax.
Officials blew up a suspicious package and detained the three along Florida's Alligator Alley after an all-night search for two vehicles thought to be involved in possible terrorist activity.
Collier County Sheriff Don Hunter said the men's comments in a Georgia restaurant may have been a joke.
Police had been searching for the vehicles after an alert restaurant customer in Calhoun, Ga., notified them that she had overheard three men of possibly Middle Eastern descent joking about the Sept. 11 attacks and discussing what could be a terrorist plot.
"If this was a hoax, they will be charged," Hunter said.
The two cars with Illinois plates were pulled over at about 1 a.m. ET after running a toll booth on Alligator Alley, the portion of Interstate 75 that connects Florida's east and west coasts.
"[The men are] being detained, and the investigation continues, but they're not suspects," Florida Gov. Jeb Bush said in an afternoon press briefing.
A law enforcement official in Washington, who spoke only on condition of anonymity, told the Associated Press that authorities had not found a terrorist connection and that the three men appeared to be medical students going to a medical conference in Miami.
The official said the men's nationalities are Jordanian, Iranian and Pakistani, and at least two are naturalized citizens.
A Florida law enforcement source said the men had received medical training from Ross University on the Caribbean island of Dominica, and that they were headed to a Miami hospital for training.
Law enforcement officials told Fox News that the detained men had no known terrorist connection and that medical equipment in the cars may have caused bomb-sniffing dogs to detect suspicious materials.
Eunice Stone told Fox News she was at a Shoney's restaurant in Calhoun with her son, Joshua, on Thursday morning when three men at another table "started talking and laughing about 9/11."
She said they joked about how they had celebrated the terror attacks at a party the night before, and that they spoke ominously about a terror attack planned for Friday.
"It really scared me, I was really scared," Stone said. "Why were they sitting there laughing about 9/11?"
She said at least one of the men had a beard that came to his chest and was wearing a Muslim skull cap, or kufi. The other two men were clean-shaven, she said.
All three were in their mid-20s and spoke English. "They were all well groomed," she said.
"The one with the beard on his face, he held up two thumbs and said, 'Yeah, did you see him smiling at how sad they were? They think they were sad on 9/11, wait until 9/13.' That's exactly what he said.
"The guy in the beard said, 'Do you think we have enough to bring it down?' Then the other guy said, 'If we don't have enough to bring it down, I have contacts that can bring it down.'
"Then they started talking about Miami, they said they had to get on to Miami."
She said she listened closely, and one of the men started talking about "bringing it down" in Miami.
"They were determine to bring 'it' down, whatever 'it' is," she said. She said the three men got up to pay their bill, and she and her son got up to follow them.
As one of the men paid the bill with a credit card, she took a crayon and wrote down the make and model of the car, as well as its Illinois license plate number.
"I just thought something is not right," she said, so she called the Georgia State Patrol on her cell phone.
She said later that her son told her at the time, "Mama, they're just messing with you."
But Stone told Fox News that whether or not it was a joke, she still believed she did the right thing.
"What she reported would lead a reasonable person to believe a criminal act was pending," said Vernon Keenan, acting director of the Georgia Bureau of Investigation.
The Georgia agency issued an advisory for the men's cars, and the cars were pulled over in Florida early Friday after one ran a toll booth on Interstate 75, said Lt. John Bagnardi of the Florida Highway Patrol.
He said the three people were initially uncooperative and refused to allow a search, so authorities brought in the bomb-sniffing dogs.
The dogs alerted authorities to material in both cars, but no explosives were immediately found, said E.J. Picolo of the Florida Department of Law Enforcement.
"We've been out here ever since in an attempt to clear those vehicles and fully identify the occupants to determine if any threat exists," Picolo said.
"Later in the day, Sarah Eltantawi of the Muslim Public Affairs Council read statements from the aunt and the father of one of the detained men, insisting the man was a native of Detroit with no ties to terrorism.
"He is very nice, warm person, a good Muslim who tries very hard to help others," the aunt said in her statement. "He is a very caring and loving individual and never been rowdy.
The father said:
"This lady in the restaurant didn't like them or something . . . fabricated the whole thing and called the FBI. It is unbelievable to me the FBI would chase, stop them, and harass them because an untrained woman that has probably never interacted with a Muslim or anyone that is not like her, said so."
Police traced one of the license plate numbers to two brothers who live in Hanover Park, a Chicago suburb. One of the brothers was briefly taken into custody, but he was later released, and police said he had no connection to the incident in Florida.
More than 14 hours later, the cars remained on Alligator Alley, about 50 yards apart, and a 20-mile stretch of the highway remained closed.
Police continued to detain the three men at the site.
Fox News' Orlando Salinas, Carl Cameron and The Associated Press contributed to this report.