Scene of attack where French teacher was decapitated

For the second time in three weeks, terror struck France, this time with the gruesome beheading of a history teacher in a street in a Paris suburb.

The suspected attacker was shot and killed by police.

French President Emmanuel Macron denounced what he called an “Islamist terrorist attack” and urged the nation to stand united against extremism.

The teacher had discussed caricatures of Islam's Prophet Muhammad with his class, authorities said.

The French anti-terrorism prosecutor opened an investigation for murder with a suspected terrorist motive.

Four people, one a minor, were detained hours later, the office of anti-terror prosecutor Jean-Francois Ricard said without elaborating.

Police typically fan out to find family and friends of potential suspects in terror cases.