Police randomly inspected commuters' bags, installed high-tech video cameras for monitoring and restricted some air flights Friday as Boston prepared for the first political convention since the Sept. 11 (search) terrorist attacks.

More than 100 high-tech video cameras were set up near the FleetCenter, site of the convention, and on downtown buildings to monitor the movements of thousands of delegates, journalists and visitors expected into the city.

The Federal Aviation Administration (search) planned to ban all corporate and private flights in and out of Logan International Airport during the convention beginning at 7 a.m. Monday to 2 a.m. July 30. Only regularly scheduled commercial flights, law enforcement, military and emergency medical flights will be allowed within a 10-mile radius of the airport.

The U.S. Coast Guard planned to use infrared and night-vision cameras in Boston Harbor and to randomly board commercial ships for security checks. Boats were banned from a 250-foot security zone around the airport, located on the edge of Boston Harbor, from Saturday through July 31.

Liquefied natural gas tankers, which normally make their way through the harbor to a terminal north of the city, were halted for the convention.

"We've trained for months, with federal, state and local law enforcement, and we're prepared," said Beverly Ford, a spokeswoman for the Boston police.

Miles of roadways and a major subway stop also were closing.

Inside the FleetCenter, toilet paper holders, soda machines and soap dispensers bore small, red stickers that would tear if the boxes were opened. Ann Roman, spokeswoman for the Secret Service (search) at the Joint Information Center in Boston, confirmed that stickers were part of the secret service's security measures.

The FBI also issued a warning to television crews, saying it had received unconfirmed information that a radical domestic group is planning to disrupt the convention by attacking media vehicles with explosives or incendiary devices.

FBI spokeswoman Gail Marcinkiewicz would not release any other details, including the name of the group.

The FBI decided to issue the warning because the threat was specific and because there will be such a large concentration of media vehicles in Boston during the convention, said a high-ranking law enforcement official in Washington speaking on condition of anonymity because of agency policy.

"I would define these individuals as agitators. They try to do disruptive stuff, but I don't know that they could be called an organized group," the official said.

Because it is relatively easy to make a crude firebomb, such as a Molotov cocktail, the FBI wanted to make sure that potential targets were made aware of the threat to reduce the chances of injury, the official said.

There is no connection to al-Qaida or any other international terrorist group, the official said.

State Public Safety Secretary Edward Flynn said security officials have studied both radical domestic groups and terrorist groups in preparing a security plan for the convention.

"I would never assert that we've done everything that we could do, but I do feel that we've done everything that we could think of," Flynn said. "We've based all of our planning on the latest intelligence information, as well as the history of prior activities engaged in by some of the protest groups, as well as possible terrorist groups."

The Massachusetts Bay Transportation Authority became the first mass transit system in the country to randomly screen bags, a security step taken in response to the March train bombings in Madrid and concerns that terrorists could target the convention.

Civil libertarians have criticized the screening program, saying the bag inspections violate the Constitutional protection against unreasonable searches.

But some train riders said they were willing to tolerate the added security.

"I think it's fair that they are doing it and I'm happy to cooperate. I think it's appropriate given what's going on in the world today," said Joe Finnigan, 50, a facilities manager from Boston. "It should help ease people's minds."

Bags were swabbed on the outside with a sensor pad that was then run through an explosive-sensing device. Bomb-sniffing dogs were also being used. Police planned to manually search the insides of bags if neither the sensing device or the dogs were available.