The Portland police traffic unit is still working to identify the driver of a tractor-trailer truck who flattened a parking meter and struck multiple parked cars and a building last week downtown.

Witnesses watched on Friday morning as the tractor, towing a roughly 50-foot refrigerated trailer, attempted to turn into the parking lot at 39 Forest Ave., the city’s public health department.

But the maneuver was too tight for the hulking truck, and it collided again and again with obstacles in its narrow path.

Now, five days later, despite identifying a person of interest in the crash, no one has been charged, said Portland police spokesman David Singer.

State police found the tractor and the trailer outside Portland the next day, but a spokesman for the Portland department declined to say where the truck and trailer were found, whether the trailer was loaded with goods at the time of the crash, or what its origin and destination may have been.

Police also did not answer questions about who owns the truck.

“That the truck and trailer were found separately is accurate,” Singer said. “I can’t speak to details until our Traffic Unit completes their investigation.”

State police declined to answer questions and referred an inquiry back to Portland.

A video taken by a passerby shows the truck failing to negotiate the tight turn, striking a parking meter, three cars and the health department building in the process. One vehicle, a silver SUV parked on Forest Avenue, appeared to have extensive damage to its rear quarter panel and bumper, leaving mangled car parts strewn along the pavement.

Another car parked deeper in the narrow public health lot suffered front end damage, and the third vehicle, an unmarked state police cruiser, was also hit, skewing its front bumper.

Tracey Hall of Portland said she had just finished a long shift as a certified nursing assistant at Maine Medical Center and was walking home around 8 a.m. when she came upon the bizarre scene in front of the city’s Public Health offices at 39 Forest Ave. Hall recorded the incident on her cell phone.

“Oh my God!” Hall says, as the sound of metal scraped against pavement.

To free itself, the driver backed the truck onto the sidewalk and trundled toward Congress Street, turning east.

The trailer sustained considerable damage from the strike with the building, leaving a pile of yellow foam insulation and a broad scrape on a municipal sign and the building’s brickwork. No one was injured in the crash, police said.

Despite pleas from pedestrians to stop, the driver kept on trucking.

“He knocked down the parking meter like it was a twig,” she said.

The video shows that the black tractor cab had few identifying markings, and there was not an obviously visible Department of Transportation number, which is required by federal law for most every vehicle that weighs over 10,000 pounds or that is engaged in interstate commerce.