Footage of a police lockdown in progress in central Stockholm, Sweden on Thursday.

A man is reported to have entered a public building with a suspect device. One person has been arrested on suspicion of preparing to endanger the public and aggravated assault, according to local reports.

Footage of a police lockdown in progress in central Stockholm, Sweden on Thursday, apparently as a result of a bomb threat in a dispute over an impounded dog.

According to local media reports, the suspect's dog was impounded after he was found guilty of animal cruelty in 2014, and the man has been in conflict with them ever since.

The dog owner lost a recent court case in which he sought to get his animal back. Wearing a mask, he entered the municipal building carrying a black rucksack before midday on Thursday. Suspecting that the bag contained an explosive device, police locked down the local area and evacuated shops and restaurants.

The man has been arrested on suspicion of preparing to endanger the public and aggravated assault, according to local reports.