Police have condemned TikTok users who broke into a former headquarters and meddled with uniforms and equipment before posting a video on the website.
Merseyside Police said the break-in happened at its old building in Liverpool's Canning Place.
The force is in the process of selling the site but it still contains valuable police property.
A 23-year-old woman from Bath, Somerset, has been arrested on suspicion of burglary, the force added.
The force said entry had been forced on 30 December following damage to an alarm system.
Patrols attended and searched the building but the TikTok users had fled.
Assistant Chief Constable Mark Kameen said the force would "not tolerate such mindless actions".
He added: "As a result of this breach, we have re-introduced onsite security and regular high visibility patrols in and around the building.
"Although the building is not in operational use, its security while it remains our property is of paramount importance.
"Nobody has the right to enter private properties, and valuable policing resources have been diverted.
"Our investigation will determine what, if anything, was taken and we will bring those responsible to justice."