“At this stage it is believed a number of people have been stabbed. The circumstances are being assessed; the incident has been declared as terrorist-related,” the Met said.
The police issued the statement at 3:12 p.m. local time (10.12 a.m. ET).
The London Ambulance Service said it had “a number of resources attending an incident in Streatham High Road.”
Streatham High Road is a busy shopping street. Police have told people to stay away from the area.
The incident comes just two months after police shot and killed a man on London Bridge in central London after an attack that left two people dead and three others injured.
This is a developing story.