Another source...
https://www.expressen.se/nyheter/sverige/bussforaren-arash-52-i-dag-kanns-det-tufft/
Per the article, English translation...
The bus driver was arrested and detained. The police do not suspect a terrorist motive at this time. According to Expressen, an illness is behind the accident.
Interesting that the driver interviewed for his point of view in the article doesn’t appear to be a native Swede.
When do they ever? If there's a guy cutting off heads in a town square while shouting terrorist slogans the best you'll get from the cops is 'no known motive'.