At least three people are believed to have been killed from a truck being driven into crowds in central Stockholm, and reports of shots being fired in another part of the city came through as police rushed to the scene. Sweden’s intelligence agency said a “large number” of people were injured in the attack.

Swedish Prime Minister Stefan Lofven said everything indicated the event was “a terror attack,” adding that one person had been arrested so far.

The Swedish newspaper Aftonbladet reported that the truck struck people on Stockholm’s Queen Street before crashing into a department store at the Ahlens Mall in Drottninggatan as crowds ran “for their lives.”

“I went to the main street when a big truck came out of nowhere. I could not see if anyone was driving it but it got out of control. I saw at least two being run over. I ran as fast as I could from there,” a witness told the newspaper.

Witness Jan Granroth said “We stood inside a shoe store and heard something … and then people started to scream,” while another witness reported hundreds of people “running for their lives” outside the shopping mall.

Sky News reported the business that owns the truck said it was “apparently hijacked earlier in day.”

Local police issued a statement saying “there are reports of injured but we have no details on how many and how serious,” adding that “There are reports of shots being fired but they have currently not been confirmed.”