Philadelphia (CNN) -- A 29-year-old man was arrested Thursday after screeners at the Philadelphia airport found flash powder and fireworks in his backpack, the Transportation Security Administration said.
A federal criminal complaint accused Joseph Picklo of Dallas, Pennsylvania, of "attempting to carry on an explosive device on a plane," according to the U.S. attorney's office in Philadelphia.
A bomb squad was dispatched to the scene, said Philadelphia police spokeswoman Christine O'Brien. But there was "no early indication of terrorism," a federal law enforcement official said.
Picklo was being screened for a United Airlines flight to San Francisco "when a plastic bottle filled with an explosive substance was found in his luggage," the release from the U.S. attorney said.
He was stopped by TSA screeners after "it was determined that (his) carry-on bag contained several prohibited items including a water bottle filled with flash powder and M-80 fireworks," according to a TSA statement.
Joe Sullivan, Philadelphia police counterterrorism inspector, said the plastic bottle was wrapped in black tape.
The bomb squad responded in minutes and removed the material, which was being tested, Sullivan said.
"He said he was experimenting with the materials for a business he was starting. He said he forgot they were in his backpack. He told us he's self-employed in sales," Sullivan said.
Philadelphia police took Picklo into custody and he was later transferred to federal custody, the U.S. attorney's office said.
A federal defender was appointed to represent him at an initial court appearance Thursday afternoon. Picklo, who must still be formally charged by indictment or information, is scheduled to return to court Friday afternoon.
The incident occurred before 6 a.m. at a TSA checkpoint serving terminals D and E, said Victoria Lupica, spokeswoman for Philadelphia International Airport.
The checkpoint was closed immediately after the item was detected, and passengers were diverted to terminal C, she said. The checkpoint reopened at 6:18 a.m., and normal airport operations resumed, she said.
Aircraft operations were not affected, Lupica said.
CNN's Susan Candiotti and Chris Dignam contributed to this report.