An 18-year-old man has died in police custody after being detained at a shopping centre.
The black teenager had been held by security staff at Liverpool One following an incident and was in the custody of police officers when he became unwell, Merseyside Police said.
The incident happened at around 6.30pm on Wednesday evening.
The Independent Police Complaints Commission (IPCC) has now begun an investigation.
Officers are in the process of informing the man's family of his death.
A spokesman for Merseyside Police said: "An ambulance was called and paramedics arrived and took the man to the Royal Liverpool University Hospital, where he was pronounced dead by doctors.
"The force's Professional Standards Department has notified the Independent Police Complaints Commission and this is now subject to an independent IPCC investigation."
IPCC investigators were deployed following notification of the incident and are overseeing examination of the scene and the post-incident procedure.
Anyone who witnessed anything which could help the investigation is asked to call the IPCC on 0800 096 9070 or email witness@ipcc.gsi.gov.uk