Police identified the attacker as Sudesh Amman.

"The suspect has not yet been formally identified however, given the circumstance of the incident, we are confident that he was Sudesh Amman, aged 20," the Metropolitian Police said in a statement.

The suspect had been recently released from prison where he had been serving a sentence for Islamist-related terrorism offences, read the statement further.

Giving details of the attack, police said armed officers, who were part of a proactive counter-terrorism surveillance operation and were following the suspect on foot, were in immediate attendance and shot a male suspect dead at the scene.

Three people, who were injured in the attack, were taken by ambulance to south London hospitals. 

They have been identified as a man and two women.

None of them are said to be in a life-threatening condition.

Deputy Assistant Commissioner Lucy D'Orsi said: "The situation has been contained and officers from the Met’s Counter Terrorism Command are now leading an investigation into the incident. The incident was quickly declared as a terrorist incident and we believe it to be Islamist-related."

Detectives from the Met’s Counter Terrorism Command continue to carry out fast-time enquiries into the circumstances of the attack in Streatham High Road.

Search warrants are being carried out at two residential addresses in the south London and Bishop's Stortford areas respectively.

No arrests have been made and enquiries continue at pace.