Security forces were continuing their manhunt in eastern France for the suspected gunman who shot and killed three people in an attack on a Christmas market in Strasbourg on Tuesday.
Police identified the suspect as 29-year-old Cherif Chekatt, a native of Strasbourg who had been known to security services as an individual radicalised in prison and a potential security risk.
With the suspect on the run, France raised its security threat to the highest level possible, tightening its border with Germany that Strasbourg lies on.
Agents checked vehicles crossing the Rhine on the French-German frontier and the government deployed extra security personnel to the eastern French city to help with the search. German agents checked trains and pedestrians arriving into the country.
Paris public prosecutor Remy Heitz said witnesses heard him cry “Allahu Akbar” as he launched the attack on the Christmas market, killing three and wounded at least 12 others. It said he was believed to be injured before his escape, according to the driver of the taxi he used to make his getaway.
“Considering the target, his way of operating, his profile and the testimonies of those who heard him yell 'Allahu Akbar', the anti-terrorist police has been called into action," Mr Heitz told reporters on Wednesday.
No group has officially claimed responsibility for the attack but ISIS supporters were celebrating the assault on social media.
A spokeswoman for Germany's BKA criminal police said Mr Chekatt was deported to France in 2017 and was known to French authorities as an extremist. He had spent time in prison in both France and Germany, including several serious cases of robbery.
According to the German newspaper Tagesspiegel, the man broke into a dentist practice in Mainz, Rhineland Palatinate state, in 2012, making away with cash, stamps and gold used for teeth fillings.
Four years later, he hit a pharmacy in the Lake Constance town of Engen, Baden-Wuerttemberg, pocketing cash.
He was on a French watchlist but the number of individuals included on the ‘S-File’ register is around 26,000.
French authorities raided Mr Chekatt’s home, a small apartment in a rundown housing bloc, on Tuesday and detained five people for interrogation over the attack.
While authorities urged people in the area to stay inside after Tuesday's attack, Strasbourg Mayor Roland Ries told BFM television Wednesday that “life must go on” so that the city does not cede to a “terrorist who is trying to disrupt our way of life”.
The assailant got inside a security zone around the venue and opened fire from there, Mayor Roland Ries said on BFM television. He then managed to escape and his location remains unknown.
"We cannot predict how long these measures will stay in place," a spokeswoman for the German border police Bundespolizei said. "We don't know where the attacker is and we want to prevent him from entering Germany."
The attack comes after a series of extremist attacks rocked France in 2015 and 2016, the deadliest being the coordinated Paris suicide bomb and shooting attacks on a concert hall, football stadium and restaurants. Other attacks included a truck-ramming on a promenade in the southern city of Nice, a shooting on the Champs-Elysees boulevard and the beheading of a priest near the northern town of Rouen.
A German Christmas market was also the target of an attack in December 2016, when Tunisian-born Anis Amri rammed a truck into a Christmas market in Berlin, killing 2 people and wounding 56.
The attack also took place just days after protests rocked Paris and other cities around the country over living costs in what has become the deepest crisis of Emmanuel Macron’s presidency.
But there was no need for the government to declare a state of emergency as new legislation gave police adequate powers to handle the situation, French Justice Minister Nicole Belloubet told French television.