Four people have been confirmed dead and 11 others have been injured in a terror attack on Strasbourg’s celebrated Christmas market on Tuesday evening.

Strasbourg went into lockdown after the the lone gunman, a 29-year-old born in the city, started his attack near the city’s celebrated Christmas market, one of the central squares of Strasbourg, which hosts a famous Christmas market attended by millions every year.

Police say officers have exhanged fire with the gunman — who had been wounded by soldiers near the Christmas market where the shooting took place.

Witnesses said he had fired a first volley of rounds near the market and then a second a few metres further on.

“There were gunshots and people running everywhere,” one shopkeeper told BFM TV, French television network. “It lasted about 10 minutes.”

A restaurant waiter told BFM TV how staff and customers tried to save a diner who stepped outside and was shot. “We used napkins to try to stem the blood.” He said the man had died.

The anti-terrorist section of the Paris prosecutor’s office declared the incident to be an act of terrorism and announced an inquiry had been opened into “murder and attempted murder in relation to a criminal enterprise”.

France’s Interior Ministry confirmed a “serious public security incident” in the city and warned residents to stay indoors.

France has been hit by several extremist attacks, including the 2015 Paris shootings, which killed 130 people and wounded hundreds, and a truck attack in Nice that killed dozens in 2016.

Some Strasbourg residents have reported on social media that they heard gunfire in some parts of the city center.

Prime Minister Edouard Philippe tweeted that “the situation is still underway, priority is given to security forces and rescuers.” President Emmanuel Macron has adjourned a meeting at the presidential palace on Tuesday night to be able to monitor the events, his office said.

Place Kleber hosts an annual Christmas market, which is known for its grand Christmas tree.

The shooting comes at a time when French security fores are stretched after more than three weeks of anti-government demonstrations.

Nearly 90,000 police were deployed on Saturday for the fourth round of protests by so-called “yellow vests” which led to violence in many cities.

It comes two years after a truck was deliberately driven into the Christmas market next to the Kaiser Wilhelm Memorial Church at Breitscheidplatz in Berlin, leaving 12 people dead and 56 others injured.

Strasbourg, about 500 kilometers (310 miles) east of Paris, is the seat of the European Parliament and on the border with Germany.