There was chaos at Ealing General Hospital yesterday when a gang fight exploded in the A&E department.
One man was stabbed to death and a female police officer had her rib broken.
The 21-year-old dead man had been killed earlier in West London - his family arrived at the hospital as the man suspected of the murder was admitted also suffering knife wounds.
Doctors and patients fled as the two warring clans and grieving family brawled in the emergency ward.
Police had to close the unit for six hours.
Murder detectives believe the second man was stabbed in revenge for the earlier killing in Willow Tree Lane in Hayes, at 1pm yesterday.
After the fight the 27-year-old suspect was transferred to another hospital - he has since has been arrested in connection with the killing.
Four Londoners stabbed to death this week
The victim is believed to have been stabbed up to eight times. He is the fourth Londoner to be stabbed to death this week.
Locals described the fatal fight on Wednesday as menacing and could hear people with dogs chasing each other through the streets.
A Scotland Yard spokesman said:
"We were called at 1.05pm to Willow Tree Lane to reports of a fight and we found a man, believed to be 21, suffering stab wounds at the scene. He was taken to hospital and pronounced dead.
At 2pm we were called to Ealing Hospital where a man of 27 had attended with stab wounds. He is in a stable condition at a separate hospital.
He has been arrested in connection with the Willow Tree Lane incident."
Two other men and a woman have also been arrested in connection with the fatal stabbing.