The attack took place on Monday, with several teenagers later arrested after the incident, Swiss media outlet 20 Minutes reports.
The incident took place after a member of the Friborg transit authority (Freiburger Verkehrsbetriebe) contacted police after a teenager refused to wear a mask after being told by a bus driver to do so.
Masks have been compulsory on all public transport in Switzerland since Monday, July 6th.
A person aged 15 attacked the bus driver after an argument ensued when police arrived.
When police intervened, they were also attacked. Police called for reinforcements, with four people between the ages of 14 and 18 arrested.
According to police reports published Tuesday, the two officers were injured during the incident.
Switzerland was the last of its neighbours to introduce a mask requirement, doing so more than two months after authorities in Germany, Italy, France and Austria.
In neighbouring France in early July, a bus driver was attacked and later died after being badly beaten by passengers who refused to comply with the country’s mask requirement.
As a result of the attack, two people in their early 20s were arrested and charged with attempted murder – while some of the bus driver’s colleagues refused to work until they were given more protection.