What is the reasonableness of a police officer's belief that detaining defendant, even briefly, was necessary to protect their safety?

The reasonableness of the police officers' belief that detaining defendant, even briefly, was necessary to protect their safety must be evaluated from the perspective of the police officers who entered the apartment. They were entering a residence, the exact floor plan of which they were unaware, to arrest a juvenile they had been told may be present, when they encountered individuals whose identity and relationship to the juvenile they were seeking was unknown. Faced with these circumstances, any reasonable person would find an initial detention of the individuals encountered was necessary to ensure the safety of the police officers. (See People v. Thurman, supra, 209 Cal.App.3d at p. 823, 257 Cal.Rptr. 517 ["To require an officer to await an overt act of hostility ... before attempting to neutralize the threat of physical harm which accompanies an occupant's presence in a probable drug trafficking residential locale, would be utter folly"].)