A man stabbed his former partner to death in front of their young son and then threw himself under a train.
The 32-year-old mother was knifed repeatedly shortly after collecting her three-year-old son from a nursery close to the Old Actonian Sports Ground in Gunnersbury Drive, Ealing, west London.
It is thought her estranged partner, who is believed to be the boy's father, approached the car before leaning in through an open door and stabbing her as she sat in the driver's seat.
Their son was sitting in the back of her car at the time and is believed to have witnessed her brutal murder.
He is now being cared for by members of his mother's family, who have been left distraught by her death.
It is thought several other mothers picking their children up from the nursery witnessed the attack, which happened in broad daylight at just before 5pm yesterday. They will be interviewed by police later today.
Just 20 minutes after the stabbing, the victim's former partner, a 37-year-old man, walked into nearby Hanwell station and threw himself in front of a London-bound train from Bristol.
Police will be speaking to horrified commuters who witnessed the incident and studying CCTV footage from the station, but they are treating his death as non-suspicious at this stage.
The woman, who has not been named by police, was taken to New Ealing Hospital, but she was pronounced dead at 5.40pm. She had suffered multiple stab wounds.
Detectives recovered what they believe is the murder weapon, apparently a kitchen knife, from inside the car.
The incident is being treated as domestic-related and police are not looking for anyone else in connection with either of the deaths.
Officers are likely to investigate the background to their relationship in the lead-up to the stabbing to establish why it happened.
Both the woman and her former partner are from the Ealing area.
A Scotland Yard spokeswoman said: "We believe we know the identity of both parties and next of kin have been informed but at this time no formal identification has taken place.
"We can confirm we are linking the two incidents, which we believe are domestic-related. The police are not searching for anyone else at this time in connection with this enquiry."
The man's death caused huge disruption on the mainline rail route between London and Bristol, leaving thousands of commuters stranded.
The train which hit the man was the 3.30pm service from Bristol Temple Meads.
First Great Western said it closed all lines in and out of London Paddington.
A spokeswoman for First Great Western said the incident caused customers "massive disruption and delays at peak time".
Paddington-bound trains were then forced to terminate at Reading in Berkshire where passengers were being transferred every 30 minutes to Waterloo.
The spokeswoman said customers were transferred to other operators to continue their journeys and by 6.50pm, two lines had reopened.
Anyone with any information is asked contact the incident room on 0208 247 7821 or Crimestoppers anonymously on 0800 555 111.Reuse content