Miami, Florida (CNN) -- The scare that closed the Miami International Airport for more than seven hours Friday morning was caused by a 70-year-old scientist who had a metal canister in his luggage that "greatly resembled a pipe bomb," a U.S. government official told CNN.
The item "tested negative for explosives but is being further tested for other contaminants," Nicholas Kimball, a Department of Homeland Security spokesman, said in a statement. "The investigation is ongoing."
"So far there is nothing nefarious," the government official said.
The man was detained but was not arrested and may be let go, the official said.
FBI Agent Michael Leverock said the man was cooperating with authorities and the item was being tested at a lab.Most of the airport was closed for hours as a bomb squad team dealt with the suspicious item, which inspectors found when screening a checked bag.
A source close to the investigation told CNN that the passenger was an American and has a history that includes incarcerations. It was the man's history along with the suspicious item that ramped up concern, the source said.
All concourses at the airport except for Concourse J were closed before the situation was resolved, police said.
Concourses E and F were evacuated at 9:30 p.m. ET Thursday after the item was found, said Greg Chin, a Miami-Dade Aviation Department spokesman. Authorities rerouted arriving flights to other parts of the airport.
The passenger who was in custody came into Miami on a flight from Brazil, Chin said.
Investigators from Miami-Dade Police, the Transportation Security Administration and the Department of Homeland Security responded to the incident, the Transportation Security Administration said in a statement. Airport roads were also closed "to ensure public safety," the statement said.
The incident brought the usually bustling Miami airport to a halt for hours.
Debbie Casanova was one of many people caught in the traffic jam outside airport terminals during the incident.
Casanova said she waited for her husband to come out of the airport for more than an hour and the wait continued even after she picked him up.
"We have been siting here for two hours," said Casanova, as she sat in her car with her husband, Roberto. "It is frustrating, but it is better to know everybody is safe."
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