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

The Paris prosecutor’s office said a security guard tackled the attacker who was taken into police custody following the incident at 7.35am.

One of the injured was in a serious condition, French police said.

The Paris police chief, Laurent Nunez, said the suspect attacked passers-by with a hammer and a knife. The seriously injured person was undergoing surgery, he said.

Soldiers patrol inside the Gare de Lyon station Soldiers patrol inside the Gare de Lyon station following the attack (Christophe Ena/AP)

He said the attack did not appear to be terror-related and that the suspect seemed to suffer from mental health issues. The suspect was carrying residency papers delivered in Italy, he said.

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

Posting on social media, 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.

Police investigators work inside the Gare de Lyon stationPolice investigators work inside the Gare de Lyon station (Christophe Ena/AP)

The Games will begin 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.

The Gare de Lyon is one of the busiest railway stations in Paris. It is a hub for high-speed trains that link the capital to other cities and for commuter trains that serve the suburbs and towns in the Paris region.