Police detained a 16-year-old on suspicion of shooting and killing three people during an incident in Sweden on Tuesday. A murder investigation has been launched, but there is currently no information about whether it was a terror attack or hate crime, police said. The incident unfolded at a hairdressers in the city of Uppsala, with witnesses saying they head five shots and saw people running for cover.

A police spokesperson added that there was information to suggest someone had left the scene on an electric scooter, but it is not yet known whether they had any involvement. Uppsala is roughly 43 miles north of Stockholm, Sweden's capital, and has seen multiple gang-related shootings outside the city centre in the past decade.

One witness told Swedish TV channel TV4: "Everything happened so fast. It just went bang, bang, bang."

Another said he was at home cooking when he heard "two bangs that sounded a bit like fireworks". He was left "very surprised and scared" as "swarms of police and ambulances" began cordoning off the street.

Henrik Envall, who runs a record store nearby, said: "To be honest, you start to get used to it, but it's not pleasant at all."

The shooting happened on the eve of the Walpurgis festival, which marks the beginning of spring and brings large crowds onto the streets.

Justice Minister Gunnar Strömmer called the shooting a "brutal act of violence".

He added: "A brutal act of violence has occurred in central Uppsala... this is at the same time as the whole of Uppsala has begun Walpurgis Night. What has happened is extremely serious."

The police's initial assessment is that this was an "isolated incident" and there is "no danger to the public".

Its spokesperson Magnus Jansson Klarin said: "We are working full-time and have a lot going on now. We see no danger to the public here and now, I want to be careful to emphasize that since many people are out celebrating."