The man, whom authorities have not identified, had not been charged with a crime as of Thursday evening, Richard Marianos, a special agent with the Bureau of Alcohol, Tobacco, Firearms and Explosives, said at a news conference.
According to authorities, the man dropped a 40-ounce bottle filled with an unknown substance and bearing a lit fuse into the food court about 12:09 p.m. Thursday.
County police said that the bottle shattered but that there was no fire or explosion and no injuries reported.
Authorities had not identified the substance in the bottle as of Thursday evening. It “appears to be gasoline,” said county police spokesman Dustin Sternbeck. Marianos called it a “flammable liquid.”
It was not known why the liquid in the bottle didn’t ignite, Marianos said.
Investigators found three other crude incendiary devices in the area of the mall where the suspect was seen, according to an ATF spokeswoman.
The mall was evacuated, although some shoppers were allowed to dine at certain establishments after the incident. Eastbound Wilson Boulevard was closed near the mall as police set up a perimeter, according to Sternbeck.
“You could see where [the bottle] hit,” said Sewell Truitte, 44, assistant parts manager at Mercedes-Benz of Arlington, who went to the mall for lunch at Panera Bread shortly after the incident.
“It’s just crazy that stuff like this happens.”
Officials released a description of the suspect after receiving a tip from a customer at the Cheesecake Factory in Clarendon about 2:30 p.m.
About 50 minutes later, authorities said, the man was found and detained.
The man was being interviewed by the police, the FBI, ATF and other agencies, according to Marianos.
“We want to find out what’s inside his head,” he said. “What would cause an individual to terrorize a local mall at lunchtime?”
Investigators were trying to learn the man’s address so they could obtain a warrant to search his home Thursday evening, according to a law enforcement official who spoke on the condition of anonymity because the investigation was continuing.
Forest City Enterprises, based in Cleveland, owns and operates the mall.
Gary Adams, assistant general manager, referred questions to county officials.
Jonathan O’Connell contributed to this report.