A man armed with a knife and a hammer has left three people injured in an early morning attack at the Gare de Lyon train station in Paris.

It marks another nerve-rattling security incident in the Olympic host city before the Summer Games open in six months.

The man, who was carrying residency papers from Italy and medicines suggesting he was undergoing treatment, was quickly taken into police custody following the attack at 7.35am (6.35am GMT) in one of the bustling station’s halls, authorities said.

Millions of passengers ride the transport hub’s high-speed trains that link Paris to other cities and its commuter train services to the suburbs and towns in the Paris region.

Laurent Nunez, the Paris police chief who is also in charge of the security operation for the July 26-August 11 Olympics, said: “This individual appears to suffer from psychiatric troubles.”

While stressing that the police investigation is still in its early stages, Mr Nunez said: “There are no elements that lead us to think that this could be a terrorist act.”

The suspect attacked passers-by with a hammer and a knife, seriously wounding one person and two others more lightly, Mr Nunez said.

A fourth person who was “very shocked” could also be counted as lightly injured, he said.

The person who suffered the most serious injuries in undergoing surgery.

Passers-by intervened to help railway police officers detain the suspect, who is in police custody, Mr Nunez added.

He said the suspect was carrying residency papers delivered in Italy, allowing him to travel legally to other European countries. The man’s nationality was not given.

Investigators are analysing the knife and hammer, the Paris prosecutor’s office said. It said the police investigation is looking at a potential preliminary charge of attempted murder.

Posting on social media, French interior minister Gerald Darmanin described the attack as an “unbearable act”, and thanked those who detained the assailant.

Security in Paris is being ramped up as it prepares to welcome 10,500 Olympians and millions of visitors for the first Olympic Games in a century in the French capital.

The Games are to open with a massive open-air ceremony along the River Seine on July 26, a major security challenge in the city that has been repeatedly hit by terror attacks, most notably in 2015.

Most recently, a man targeted passers-by near the Eiffel Tower in December, killing a German tourist with a knife and injuring two others.