An investigation has been launched by the police watchdog following the death of a man who was restrained using pepper spray.
The Independent Police Complaints Commission (IPCC) has begun an inquiry after the man died in hospital shortly after he was arrested by police in Widnes, Merseyside on Monday night.
A number of officers were called to an address in Lacy Street, Widnes, at around 5.15pm.
They arrested a 25-year-old man for alleged affray.
A spokesman for the IPCC said: "During the course of the arrest it is understood police deployed pepper spray."
The man, who has not yet been named, was "restrained" and taken by police van to Runcorn police station, the spokesman said.
He added: "Shortly after arrival he became unwell and paramedics were called.
"He was then taken to Warrington General Hospital by ambulance where he was pronounced dead at 7.09pm."
The IPPC said investigators were deployed to Widnes to begin gathering evidence and take initial accounts from police officers.
A post-mortem examination is due to be carried out later.