A 18-year-old woman died today after plunging from the 17th floor of a flat as police raided the address in Woolwich, south-east London, Scotland Yard said.
Scotland Yard said she fell from her bedroom window before officers arrested a man on suspicion of assisting an offender.
The incident at a tower block in Woolwich, south east London, has been referred to the Independent Police Complaints Commission (IPCC).
The woman fell when police arrived at her address in Mulgrave Road at 9.30am "to carry out an arrest inquiry".
The Metropolitan Police's Directorate of Professional Standards (DPS) has also been called in to investigate the plunge.
A spokesman said: "Shortly after the officers entered the flat, a woman, who is believed to be 18, fell from a bedroom window on the 17th floor.
"She was pronounced dead at the scene. We await formal identification. A post-mortem examination will be scheduled in due course.
"A man was arrested by officers on suspicion of assisting an offender and is currently in custody at a south London police station."