Man shot and wounded after attacking police officer at Notre Dame, France

A man has been shot and injured after attacking police officers with a hammer outside Notre Dame cathedral in Paris.

The world-famous landmark, which is visited by millions of people a year, was locked down during the incident.

Hundreds of tourists were kept inside the cathedral as armed police responded - and one picture showed visitors with their hands in the air.

One officer was wounded during the assault in the cathedral's courtyard before the lone attacker was "neutralised".

Reuters reports that the attacker was shot in the thorax and has now been taken to hospital - but his motive remains unclear.

Although the hour-long operation at Notre Dame has ended, France's counter-terrorism office has opened an investigation.

Robbie Thomas, who was visiting Notre Dame at the time, told Sky News that "probably a couple of thousand" people were inside the cathedral when the attack began.

He said everyone had remained calm and were "trying not to panic" as they awaited announcements from police.

"A man I spoke to ran in from outside because he heard gunshots," Mr Thomas said.

One holidaymaker tweeted: "Not the holiday experience wanted. Trapped in Notre Dame Cathedral after police shoot a man. We are with our 2 terrified children."

Those who were trapped inside were gradually being allowed to leave once "usual" security checks had taken place.

Paris is on high alert following a series of Islamic extremist attacks in recent years - with soldiers patrolling the city's streets along with police to protect tourist sites, government buildings and events.

In September, three women were arrested after police found a car loaded with gas cylinders abandoned near Notre Dame - with France's interior ministry saying it was likely to have been an imminent attack.