The crashes occurred outside of Örebro, central Sweden, on the E20 highway, and began when a school bus, a tourist coach, and a tanker truck rear-ended one another. One of the buses in the accident was carrying school children on a study trip to Stockholm from Skara.
"Many people started screaming and I wondered what happened," 16-year-old Emelie Johannesson, who was half asleep at the time, told the Aftonbladet newspaper.
As traffic continued to stretch out along the highway, another two accidents were reported, one of which involved a fatality.
IN PICTURES: See the damage from the Örebro crash
Around 60 people were taken to the Örebro University Hospital, which declared a state of crisis and had to clear its emergency room to take in more patients.
"This means that we are working with redirecting all conceivable resources in the hospital so we can take in all the patients," hospital spokeswoman Ulrika Julin told the TT news agency.
Up to ten people were reported to be seriously injured, although no one has sustained injuries that were deemed life threatening.
Other motorists, meanwhile, saw long queues as an emergency team cleared the highway of debris.
This story has been updated
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