A suspected rapist who abducted two women threatened to kill a builder who helped them escape.
The women, aged in their 20s, got away from the attacker on Thursday afternoon. He had snatched them separately in London earlier that day.
A man, aged 33, has been arrested on suspicion of conspiracy to rape.
The hunt for the suspect, who has a distinctive tattoo of the name Bobbie on his stomach, continues. Police say he is a danger to women.
The first victim was taken in Chingford, north London, at about 00:30 BST, while the second was targeted 12 hours later in Edgware.
Both women were raped.
The suspect drove the women to a hotel in Watford and attempted to book a room at about 13:00, but left when this was unavailable.
The women escaped in Osbourne Road, Watford, at about 14:30.
The boss of construction company Green Contractors Ltd, who wished only to be named as Alex, said two members of his staff were crossing Osbourne Road, where they were working, when one of the women jumped out of the car.
He said the attacker “went after her really pulling her by the hair, when the girl started to scream ‘Help, help, help'”.
He said: “One of my workers went towards the victim and shouted ‘Leave it, leave it’ and punched the perpetrator.
“[The attacker] released the girl and started to get into a fighting position to fight back to the worker.”
Other builders came to help their colleague, and one of the women hit her abductor over the head with a bottle.
He then fled, telling the rescuer: “My friend, you’re dead.”
The suspect is described as a white man of muscular build, in his late 20s or early 30s, with a bald head or shaved blond hair and a light-coloured short beard.
The car he was driving is believed to be a silver or grey Ford S-Max people carrier, with false registration plates.