A rush-hour accident in Etna, Maine, left a stretch of Interstate 95 clogged with what a police spokesman described as a “giant pile of metal” on Wednesday morning. The accident, occurring at about 7:30 a.m., involved cars, a tractor-trailer and a school bus, and caused a series of chain reaction crashes that left a pileup of more than 70 vehicles. At least 17 people were injured, some seriously.

Both lanes on a 30-mile stretch of highway were closed for five hours. According to police, more than 25 vehicles were involved in the main crash, followed by a series of other wrecks leading up to the site. Some of the crashes involved two or three vehicles. Other vehicles then went off the road to avoid hitting other stopped cars. One state trooper described the site as a “giant pile of metal.”

State police lieutenant Sean Hashey, who said he was shocked that there were no fatalities, said the crashes were most likely the result of slippery roads, poor visibility and speed. However, he said that it would never be known exactly what happened that triggered the chain reaction of accidents, which is that largest seen in Maine in 15 years.

Emergency personnel were forced to climb over and on top of cars to reach motorists who were stranded in the middle of the piles of vehicles. Some people suffered broken bones and one person had a heart attack. Students on the school bus were shaken up but not injured.

People involved in the crash gathered at a nearby travel stop to give statements to police and wait for their wrecked vehicles. Workers reported seeing over a dozen ambulances attempting to get on the highway. Some people were stuck, although not actually part of the accident. Rose Butts said she swerved to miss the pile-up and ended up in a snowbank, where she waited over five hours for help.

Although heavy snow was falling over much of Maine Wednesday morning, according to the National Weather Service there was only about an inch of snow on the ground at the time of the crash. The forecast calls for five to nine inches of accumulation throughout the day.