Shoppers were left stranded for almost seven hours because of a man threatening to jump from the top of a car park.
Five roads in Uxbridge town centre were closed last Wednesday after police were called to the incident at Cedars car park shortly after 6pm.
It took police negotiators and The Samaritans until 1am on the
Thursday to convince the man, who was aged between 35 and 40, to come down to be taken to Hillingdon Hospital.
Inspector David Partridge said: "We received a call from a member of the public saying there was a male on the seventh floor standing on the ledge.
"When we attended the male was balanced fairly precariously on the ledge of the car park and it was his intention to jump. He was wrestling with himself as to whether to throw himself off or not.
"He was not very forthcoming at all, so we called in our negotiations team from Scotland Yard.
"We had to cordon off the area to prevent any harm to other members of the public and to try to restrict cars coming past for obvious reasons, and to limit the audience.
"It caused a fair amount of chaos and inconvenience for which we apologise.
"It's not a common occurrence but unfortunately it does happen."
Six police units, two ambulances and the fire brigade were called to the scene and Oxford Road, Harefield Road, High Street, Belmont Road and York Road, were all closed.
No cars were allowed to leave the car park and buses had to be diverted.
Did you see what happened or were you one of the drivers left stranded in the car park? Contact the newsroom on 01895 451029 or visit www.uxbridgegazette.co.uk