A massive hunt was underway on Wednesday for a gunman who opened fire near a Christmas market in the French city of Strasbourg, killing three people and injuring 12 others, police said.

More than 350 police gendarmes (paramilitary police officers) and soldiers supported by air units have been mobilised to find the 29-year-old suspect, who was already known to security services as a possible threat.

The Paris Prosecutor’s office told CNN that their anti-terror section is in charge of the investigation.

Strasbourg’s famed Christmas Market is one of the oldest in Europe and draws millions of visitors each year.

The suspect entered the perimeter of the market by the city’s Corbeau Bridge and began shooting at passers-by on the Rue des Orfevres at 8 pm, on Tuesday, when many were in the middle of their Christmas shopping.

Anti-terror police descended on the market and attempted to apprehend the suspect, who French media reported was injured in one of the exchanges.

The suspect is then believed to have jumped into a taxi and fled the scene.

The attack prompted France to raise its national security threat level to its highest “emergency terror attack” status, Interior Minister Christophe Castaner said at a press conference.

Regarding the suspect, Castaner told reporters on Wednesday, adding that he was known for non-terror related offences.

French gendarmes had attempted to bring him in for questioning on Tuesday morning before the attack but found he wasn’t home, a spokesperson for France’s National Police told CNN, without providing further details.
Of the 12 injured, six people were in critical condition, authorities said.

Strasbourg, a picturesque city of about 300,000 in France’s Grand Est region on the border with Germany, has previously been at the centre of French counter-terrorism operations.

The market itself was targeted 18 years ago in a thwarted plot by Al Qaeda-linked terrorists.

In 2016, French authorities arrested seven people in anti-terror raids in Strasbourg and Marseilles.

In 2012, police killed one suspect and arrested 10 others in the city as part of coordinated counter-terrorism operations.