At 20.30 on Thursday, several people are said to have broken into a family's apartment on Gärdet in central Stockholm.
The persons must have been armed with a pistol-like object and forced a valuable object on themselves, before leaving the apartment on foot.
According to the police, the object has a relatively high value.
Several police patrols and helicopters are now chasing the suspected perpetrators.
Several neighbors in the property are said to have witnessed the incident and the police are knocking on doors in the area.
The incident is classified as aggravated robbery and aggravated weapon crime.
No person should have been physically injured, according to police.
The apartment will be examined by police technicians.