Kyle Aldridge died after stepping off a parade float being driven by his grandfather, who was preparing to steer onto the Annapolis route for the annual Fourth of July procession of dance teams, antique firetrucks and hand-shaking politicians.

The 7-year-old's death came during a longstanding tradition in Annapolis, not unlike local parades organized in communities across Maryland on Independence Day. The popular event is held in the evening before a display of fireworks is launched from a barge off City Dock.

At about 7:10 p.m. Thursday, police said Kyle stepped off a trailer being towed by a 2005 GMC van driven by his grandfather, 43-year-old Jason Hicks of Glen Burnie. The boy was run over by the trailer, according to police, who are investigating the incident.

"From what we know, it's just a very, very tragic accident," said Annapolis Mayor Josh Cohen, who visited the boy's family at Anne Arundel Medical Center, where he died.

Cpl. Amy Miguez, a spokeswoman for the Annapolis Police Department, said investigators are reviewing a video security system at a nearby business that caught the incident on tape. They also are checking reports that the boy's clothing may have gotten caught on something, and determining whether the weight and speed of the vehicle were factors that contributed to his death, she said.

"It appears that the boy was getting off the side of the trailer at the behest of someone walking along the trailer," Miguez said.

Police do not believe that driver error, drugs or alcohol played a role in the crash.

"There's not really any question of any fault being assigned. It's an accident, truly," Miguez said.

Aldridge's family and Hicks could not be reached.

The boy was on a float owned by iWHEELiE.com that featured a motorcycle with its rear wheel mounted to the trailer. According to the company's website, iWHEELiE.com takes the attraction to events around the region, offering people the chance to simulate wheelies and other motorcycle tricks. It can be rented for parties and events.

A phone message left with the company was not returned.

This year's parade also included Irish dancers, flag twirlers, antique trucks, candidates for this fall's city elections and a contingent of activists from the group Save Annapolis who are opposed to City Dock redevelopment plans and held signs reading, "Annapolis is for sailing, it's not for sale."

Hicks' van was sixth from the end of the 49-vehicle parade, said Michelle LeFurge, events coordinator for the city of Annapolis. The parade continued after the incident, and the fireworks were staged as planned.

With an increased presence of emergency officials for the holiday, a police officer was at the scene within one minute and the Annapolis Fire Department arrived within two minutes, Miguez said.

"This kid had help there immediately," she said.

The incident happened on Amos Garrett Boulevard, a mostly residential side street where parade participants line up before embarking on West Street heading toward downtown Annapolis.

Employees at Car World, a used-car dealership on the corner of Amos Garrett Boulevard and West Street, confirmed that they provided a security video to police that had captured the incident, but they declined to be interviewed.

Parades in Annapolis are regulated by the mayor's office. Participants are required to submit an application describing their entry. The city's rules permit businesses advertising their goods or services to participate but require their floats to have a patriotic theme.

LeFurge said the owner of the vehicle and trailer involved in the incident complied with all requirements and presented no obvious safety issues. She said the motorcycle on the trailer, mounted in a wheelie position, appeared to be well-secured and was not a factor in the accident.

LeFurge said the city has no rules restricting children's participation in parades.