Barcelona police opened fire on a truck to stop it as it sped down the motorway in the wrong direction, carrying gas cylinders.
The vehicle rammed several cars as it sped towards the city on the Ronda del Litoral on Tuesday morning before police stopped it at one of the exits.
Some of the cylinders fell out during the chase, injuring a passerby, La Vanguardia reports.
A photo from the scene shows the truck stopped with at least two bullet holes in its windscreen.
A Swedish man has been arrested and counter-terror police are investigating, local media reported.
Spain’s Interior Minister Juan Ignacio Zoido was quick to deny it was terrorism, saying that the arrested man had “a psychiatric history”.
Photos and footage from the scene showed the truck rammed against the wall on a motorway exit, still carrying its load of butane gas cylinders.
The arrested man has been named locally as Joakim Robin Berggren.
“We detained a person who was of Swedish nationality,” a police spokesman told the AFP.
Mireia Ruiz, who saw the truck from her home, told AFP the driver ignored people’s pleas for him to stop as he sped down the wrong side of the road.
“When people shouted at him, he would laugh and make offensive gestures with his hand,” she told AFP.