The incident occurred in the central city of Västerås on Monday afternoon.
Police in central Sweden are investigating after two armed men stole students' computers from their classrooms at knifepoint.
According to officials, two masked suspects interrupted a class at Rudbeckianska high school in Västerås on Monday afternoon.
"The perpetrators then reportedly fled the school," police said in a later statement.
The suspects then tried to hijack a car near the city's cathedral before being confronted by members of the public.
A man in his 40s was assaulted and injured by one of the suspects when he tried to chase them, police added. Paramedics treated the man at the scene.
No arrests have been made, and officials say they have launched an investigation into robbery, attempted seizing of a vehicle and assault.
"In the past, electronics have been stolen from schools, but then through break-ins and from empty premises," police added in a further statement.
"The approach to yesterday's robbery stands out and is something that the police in Västerås have not seen before."
"The school should be a safe place and no one should have to be exposed to the violation and fear that the robbery has entailed," added Lars Jansson, acting head of the local police area in Västerås.