GENEVA -- Several passers-by were injured in an indiscriminate knife attack in the northern Swiss town of Zofingen on Wednesday evening, according to the local police.

Police said on social media that after the incident, special forces apprehended the perpetrator after he hid in a building for two hours.

The victims had been transported to the hospital with stab wounds, said police.

A large-scale police operation continued in the evening. The authorities advised people to avoid areas near the local train station.

It was still unclear if there was more than one attacker, police said.