MIAMI -- Three Middle Eastern men in a cargo truck sparked a brief terrorism scare at the Port of Miami on Sunday until officials determined their freight was harmless and the incident had stemmed from a simple misunderstanding.

The port's cargo area was shut down Sunday and a bomb squad moved the truck away from public areas to scan it for radioactive materials. Nothing unusual was found, port officials said.

The men in the truck -- Amar Al Hadad and Hussain Al Hadad, both Iraqis, and Hassan El Sayed, a Lebanese national -- were arrested. Amar and Hussain Al Hadad were both charged with resisting arrest; Hussain Al Hadad was also charged with trespassing, as was El Sayed.

Officials initially said the men, all permanent U.S. residents, had been caught trying to slip past a checkpoint at the port's entrance. But a judge Monday dismissed the charges, citing a lack of evidence.

The truck's contents -- electrical automotive parts in a 40-foot container -- matched the driver's cargo manifest, said Miami-Dade police spokeswoman Nancy Goldberg.

A port security officer became suspicious when Amar Al Hadad could not produce proper paperwork in a routine inspection to enter the port at about 8 a.m., Goldberg said.

He also indicated he was alone in the truck, though security officers found 24-year-old Hussain Al Hadad and 20-year-old El Sayed in the cab, she said. El Sayed was a friend and Hussain Al Hadad was the brother of the 28-year-old Iraqi driver, she said.

"Due to a miscommunication between the gate security personnel and the truck driver, we believe there was a discrepancy in the number of people in the vehicle," Goldberg said. "This, and the fact that one of the individuals did not have any form of ID, raised our level of concern."

The FBI and the Department of Homeland Security were called to the port, along with local law enforcement, "in an abundance of caution," Goldberg said. The three men were detained by the FBI and released before being charged by the Miami-Dade Police Department.

More than 20 pallets containing spools of wire and other automotive parts taken from the truck were being scanned, but no radioactive material had been found, said Jose Ramirez, a U.S. Customs and Border Protection spokesman.

The three men, of Dearborn, Mich., do not appear on any terrorist watch list, said Barbara Gonzalez, a U.S. Immigration and Customs Enforcement spokeswoman.