A woman was stabbed to death and another injured when a third woman allegedly ran amok with a stolen butcher's knife on a busy shopping street.
The two victims, both adults, were attacked as stores opened for business on Monday morning in Bexleyheath, south-east London.
The woman who died has been named in reports as law firm accounts manager Sally Hodkin. Police have not officially named the victim, who was said to have worked at law firm Cunningham Blake. A voice message on the firm's answering machine said it was closed due to a bereavement.
The suspected attacker later walked into a tile shop with blood on one hand, telling the manager to call the police because she had "hurt somebody".
Sources said the attacker bought a blade from a nearby Asda store before she attacked a 23-year-old woman waiting at a nearby bus stop, slashing her hand.
She then fled the scene, going next into the British Meat Market store, some 150 metres away, where she threatened the manager and made off with another knife, which she used to kill her second victim, 59.
The dead woman is understood to have been on her way to work when she was stabbed in the neck. She is believed to have lived locally and was pronounced dead minutes later, at 8.41am.
Detective Superintendent Keith Niven, of the Met's Homicide and Serious Crime Command, said there is no information to suggest the victims were known to each other or to the suspect.
Shops were forced to close their doors as detectives and forensic officers investigated the attacks, and part of the road was cordoned off.
The suspect, aged 32 and believed to be from London but not from the borough of Bexley, remains in custody. It is understood she was assessed for mental health problems following her arrest.