A police officer was rushed to hospital with a broken arm after being struck with a hammer while treating a stab victim in Hounslow.
Officers were called to High Street in Cranford following reports of an attack at 8.15pm on Saturday.
A 31-year-old was found at the scene with a slash wound. While treating the man, officers were attacked by a large group of people.
One officer was rushed to hospital where he was treated for a broken arm. He has since been discharged.
The stabbed victim was taken to a central London hospital for treatment.
His condition was assessed as non life-threatening.
There have been no arrests and enquiries are ongoing.