The man who sprayed gunfire at a Christmas market in Strasbourg, killing three people and wounding 13 others, was identified as a radicalized Islamist with a lengthy rap sheet who was on France’s national security list as a possible terror threat, according to reports.

Cherif Chekatt, 29, who was known to be part of radicalized networks in his native Strasbourg, is a “repeat offender” and “delinquent” who served time in French and German prisons, the UK’s Independent reported.

Senior Interior Ministry official Laurent Nuñez said on France-Inter radio that police had sought to arrest Chekatt on Tuesday morning, hours before the shooting, in connection with an attempted murder and armed robbery.

He was not at home — where explosives reportedly were found — but five other people were detained, authorities said, according to the Guardian of the UK.

Nuñez said the failed arrest might be one reason for the attack.

“Right now, the terrorist motive for this attack has not been established, and I would advise extreme caution over this. The hunt is taking place and the priority is to find this attacker,” he said.

Chekatt has been on France’s “Fiche S,” a register of those who are considered to pose a threat to national security. The S-card permits police to place suspects under surveillance, but is not grounds for arrest.

Among people on the list are suspected Islamist extremists, major criminals, political militants and anarchists.

France raised the security alert level as hundreds of police and soldiers hunted for Chekatt, who may have fled to neighboring Germany, officials said.

A cab driver, flagged down by the gunman and ordered to take him out of the city center, told authorities that the suspect had been injured during a gun battle.

“Three hundred and fifty police and gendarmes are currently on the ground to apprehend the suspect, supported by two helicopters, the RAID [French anti-terror police], the BRI [anti-gang brigade] and the Sentinel force,” Interior Minister Christophe Castaner said.

“The government has decided to move the security level to ‘Emergency Attack’ with stricter controls at the borders, and the implementation of reinforced controls on all the Christmas markets that are taking place in France to avoid the risk of copycat attacks.”

Police detained five people after raiding addresses linked to the suspect overnight, the Guardian reported.

Castaner said Chekatt was “notorious” to police and had a long criminal record, including for armed robbery.

He had been incarcerated in Germany in 2016 and 2017 on theft charges, and was deported to France in 2017, a spokeswoman for Germany’s BKA criminal police told Reuters.

“This individual is known for lots of crimes not linked to terrorism [and] spent several periods in prison,” Nuñez said.

It was during one of these stints that he was flagged because of a “radicalization in the way he practiced his religion,” he added.

Chekatt fired into the crowds at the Christmas market before engaging with soldiers from Opération Sentinelle, a nationwide security operation established after terrorist attacks in Paris in 2015, the Guardian reported.

Police said three people were killed and 13 injured, eight of them seriously.

Strasbourg’s Christmas market, which started in 1570, has been held under tight security since the Paris attacks. Access to the area is controlled and visitors’ bags are searched.

The assailant got inside a security zone around the venue and opened fire from there, Mayor Roland Ries told BFM TV.

The attack is a new blow to France, which experienced a slew of Islamic extremist killings in 2015 and 2016. It came amid a month of protests against President Emmanuel Macron that have blocked roads around the country, led to rioting and put heavy strain on police.

With Post wires