WATCH: The moment 'police shoot gunman' during Paris attack

This is the dramatic moment Parisian police took down the gunman on the Champs-Elysés who killed a policeman and left two others seriously injured.

The footage, which emerged on Twitter, shows two officers in black armour confront the man responsible for killing a police officer and seriously injuring two others.

Officers had earlier chased down the man after he shot and killed an officer with an AK-47 while stopped at a red light.

Source: Twitter

Islamic State have since claimed responsibility for the attack.

Officials say the suspect in the attack was previously flagged as an extremist, AP has reported.

Police near the scene of the shooting in Paris. Source: AP

French President Francois Hollande has promised vigilance ahead of the presidential election and expressed "immense sadness" for the police officer's death.

France's counter-terrorism office has opened an investigation into the shooting, the prosecutor's office said.