During Tuesday morning, the police were alerted about a suspicious car at a property in Frändefors in Vänersborg. According to the caller, an object was thrown from the car and then detonated.
Now three people have been brought in for questioning and one man has been arrested, the police say.
Links to gang crime
The police raided three different properties with links to a criminal network. According to the National Bomb Squad, the object was some form of homemade explosive device.
No one is reported to have been injured in connection with the explosion, but some material damage occurred. The property in question was cordoned off, but at 1:30 p.m. the police said they have been claimed.
The incident is classified as public-dangerous devastation.