Detectives have launched a murder investigation after a man was stabbed to death on a busy high street in west London.

The victim, a man believed to be aged 34, was attacked in Wealdstone on Monday evening.

A witness said the victim was stabbed in the chest. He collapsed outside a branch of Halifax shortly before 7pm as commuters made their way home down the busy high street.

Emergency services raced to the scene near the junctions with George Gange Way and Gordon Road.

The man was rushed to hospital in central London in a critical condition but died in the early hours of the morning.

Scotland Yard said he was pronounced dead at about 2.30am and his next of kin have been informed.

Forensics teams were trawling the scene of the attack throughout the night, witnesses said.

A woman, who lives on the high street and asked not to be named, told the Standard she saw a lot of blood on the floor and police stood guard at a huge cordon throughout the night.

The 47-year-old said: “I heard a lot of shouting and screams and a lot of sirens but initially took no notice as I hear those things quite a lot.

“Then my son called me to see if I was OK and said that someone had been killed outside the bank. I looked outside and it was chaos.

“There was a man dressed in white overalls taking pictures at about 3am and the forensics tent was put up just before that.

“All the shops have been closed – Asda, Boots, the gym – they haven’t been letting anyone in."

Detective Chief Inspector Mark Lawson, who is leading the investigation, said: "We believe the area at the time of the stabbing, just before 6.50pm in the evening, would have been very busy with people coming from nearby Harrow and Wealdstone station.

"We are very keen to hear from anyone who was in and around the Wealdstone High Street area that may have seen or heard anything suspicious, especially from anyone who saw people running towards the station."

There have been no arrests at this stage and enquiries continue.

Officers believe they know who the deceased is but await formal identification.

A post mortem examination will be scheduled in due course.

Any witnesses, or anyone with any information, are urged to contact the incident room on 020 8358 0200, or contact police by calling 101 or by tweeting @MetCC.

They can also call Crimestoppers anonymously on 0800 555 111 or visit crimestoppers-uk.org.