A window and a patio door were damaged, police say on their website.
The alarm came just after three o'clock when several people called the police about a loud bang.
"It was a big bang that was heard all over Helsingborg," Thomas Söderberg, a police officer in the South Region, told Aftonbladet.
National bomb protection and forensics have been called to the scene. According to Aftonbladet, the police have launched a preliminary investigation into the destruction of public property.
No person was injured.