The alarm about the incident came in just after 1 a.m. Thursday.
"When we arrived at the scene we could see that something had exploded next to the front door of a villa. It is too early to say what exploded," Torbjörn Lindqvist, a police duty officer, told P4 Jönköping.
No one was reported injured, despite there being people in the house. The National Bomb Squad has been dispatched to the scene.
The case is classified as public danger destruction.
