Three people have been killed in a knife attack in the French city of Nice, police say.
Nice Mayor Christian Estrosi said everything pointed to a “terrorist attack at the heart of the Notre-Dame basilica”.
Police said one woman had been beheaded in the attack and Mr Estrosi spoke of “islamofascism”. The suspect was detained shortly after the attack.
France’s national anti-terror prosecutors opened a murder inquiry.
The mayor told reporters that the suspect had “repeated endlessly ‘Allahu Akbar’ (God is greatest) when he was being treated at the scene”.
Mr Estrosi said one of those killed was the caretaker at the basilica.
The interior minister appealed to people to avoid the area in the centre of the French Riviera city. Gérald Darmanin said he was convening a crisis meeting at the ministry in Paris.
A minute’s silence was held in the National Assembly, where Prime Minister Jean Castex had just been giving details of lockdown measures coming into force on Thursday night.
“Without question this is a very serious new challenge that is striking our country,” he said, appealing for unity and cohesion.
Nice was the target of one of France’s deadliest attacks in recent years, when a 31-year-old Tunisian drove a truck into crowds celebrating Bastille Day on 14 July 2016, killing 86 people.