The collision of an RV and a tractor-trailer Friday afternoon on the Maine Turnpike in Saco resulted in injuries and stalled highway traffic for hours on one of the busiest travel days of the year, authorities said.

The crash happened shortly before 2 p.m. in the southbound lanes near Exit 36 in Saco, backing up turnpike traffic as much as 11 miles in both directions and clogging local roads throughout the region. With northbound drivers “rubbernecking” as they passed the accident scene, a normally busy section of Interstate 95 became a virtual parking lot for about five hours.

“It couldn’t have happened at a worse time,” said Bruce Van Note, a Maine Turnpike Authority administrator. “There’s really never a good time, but northbound traffic coming into Maine is typically high volume on a Friday afternoon in the summer, and the first weekend in August is one of the busiest vacation weeks of the year for us.”

Van Note said he didn’t have access to typical daily traffic totals on the turnpike. Traffic data on the turnpike’s website shows that August was the highway’s busiest month in 2015, carrying 8.7 million vehicles.

Following Friday’s crash, all southbound lanes reopened by 5:30 p.m. and traffic was flowing freely in both directions by 7:30 p.m., according to the turnpike authority.

Van Note confirmed that the collision caused injuries but declined to provide more information.

Maine State Police did not respond immediately to requests for information about the crash.

Hunter McGee, a freelance journalist from Derry, New Hampshire, said he was traveling north on the turnpike Friday afternoon and drove by the crash site shortly after it occurred.

McGee first saw a plume of smoke rising in the distance, then he saw motorists rushing to help at the crash scene, he said. Traffic in the northbound lanes slowed to a crawl, allowing McGee to roll down his car window and shoot photos with his cellphone as he passed.

“It was just a pile of rubble and debris,” McGee said. “I saw a man chasing after a little dog that was scrambling across the southbound lanes. I saw flames rising from the rubble, and I saw one gentleman pull out a fire extinguisher to put them out.”

As McGee exited the highway for his destination in South Portland, he passed several rescue vehicles that appeared to be heading to the accident scene, he said.

Although traffic is usually heavy in southern Maine on Friday afternoons in the summer, motorists reported severe backups throughout the area near the crash, including on Route 1 in Scarborough and Saco and on Payne Road from the Maine Mall area in South Portland to Route 1 in Scarborough.

“Anytime you have standing traffic on the turnpike, it usually has collateral impact on secondary roads,” Van Note said.

Kelley Bouchard can be contacted at:

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