The incident happened near the Greenwich Islamic Centre in Plumstead Road at around 1pm today (April 11).
Officers and London Ambulance Service crews attended and found a man who had been stabbed.
Plumstead Road mosque ‘police incident’: Live updates
He was taken to hospital for treatment where his condition is unknown at this stage.
Two men, in their 20s and 30s, were arrested on suspicion of grievous bodily harm.
They remain in police custody.
Police are also in attendance dealing with another incident in Plumstead High Street.
These are both unrelated.
A spokesperson for Metropolitan Police said: “Police were called to reports of a stabbing in Plumstead Road, SE18, at around 13:00hrs on Friday, 11 April.
“Officers attended alongside the London Ambulance Service. One man in his 30s was taken to hospital for stab wounds. There is no update on the man’s injuries at this time.
“There have been two arrests. One man in his 30’s was arrested on suspicion of grievous bodily harm. Another man in his 20’s was arrested on suspicion of grievous bodily harm. They remain in custody.
“Enquiries continue.”