At least three people were injured after a gunman opened fire outside a metro station in the city of Lille in northern France, days after the attack in London.

Armed police rushed to the scene and sealed off streets near the Porte d'Arras Metro station at around 9.45 p.m. (local time) on Friday night, the Mirror reported.

The shots, say reports, were fired at Jacques Febvrier square, a few metres from the metro station.

Witnesses reported at least three injuries, including a 14-year-old boy. The boy is believed to have been shot in the leg, said the local media. They were taken to hospital and are not in a life-threatening condition.

The wounded were reported to have been shot several times, according to French news outlet La Voix.

The motive behind the shooting is not yet known. The shooter is reported to be still on the loose.

France has suffered a string of Islamist terror attacks during the past 12 months.

It comes after a suspected Islamist terrorist was gunned down at Paris Orly airport last week after launching an attack on a police traffic patrol.

Also, a suspected terrorist was arrested in the Belgian city of Antwerp on Thursday after he allegedly tried to drive a car into shoppers on a pedestrianised street, less than 24 hours after the Westminster attack.

The vehicle was reportedly full of liquid gas, knives and rifles.

The suspected driver, in camouflage, was later arrested by the police, the local media reported.

The incident, according to reports, was being investigated as a possible terrorist incident.