An armed man has died after being restrained by customers during an attempted robbery at a bookmakers, police said.
The man, in his 50s, was believed to be wearing a gas mask and holding a gun when he entered a Ladbrokes branch on Crownhill Road in Plymouth shortly before 7pm.
Customers managed to disarm him and held him on the floor while others raised the alarm, Devon and Cornwall Police said.
Police arrested the man, who was already unconscious, but he was declared dead shortly afterwards.
"It quickly became clear the man was unresponsive and an ambulance was immediately requested by police who carried out CPR until they arrived," a police spokesman said.
"A few minutes later three paramedics arrived at the scene and continued to carry out further CPR. Around 20 minutes later the man was declared dead at the scene by the paramedics."
The Independent Police Complaints Commission (IPCC) has been informed of death.
Chief Inspector Ian Drummond-Smith said: "This is a very serious incident. We cannot speculate on what has actually taken place here today.
"A full investigation has now begun and while the IPCC carry out their investigation it is not appropriate to comment further."