A manhunt is underway for the perpetrator of the truck attack at a Berlin Christmas market in Germany, which killed 12 and wounded at least 48.

On Tuesday (20 December), German police released a suspect as there was no evidence to prove that the detained individual carried out the attack. The suspect, Naved Baluch, a Pakistani national denied any ties with the attack.

Police added that more than one person could be on the run, potentially armed. Authorities have also urged people to be vigilant and not to investigate anything suspicious.

Holger Münch, the chief of federal criminal police office, told a news conference: "We need to work on the assumption that an armed perpetrator is still on the loose. We are on high alert and are investigating every possible angle."

Islamic State (Isis) claimed responsibility for the attack but gave no evidence. The jihadist group released a statement via its Amaq agency "A soldier of the Islamic State carried out the Berlin operation in response to appeals to target citizens of the crusader coalition countries."

Interior Minister Thomas de Maiziere said: "No-one will rest until the perpetrator or perpetrators have been caught." According to the Telegraph, he added, "We cannot rule out the possibility that there will be more victims."

Berlin Mayor Michael Mueller said that the security has been stepped-up to prevent any further attacks. "The right thing is to keep your eyes open - be vigilant in this situation. But you can move around safely in public places. There is no need for panic," Mueller said.

German attorney general Peter Frank said that the style of attack and the target choice suggests that it is Islamic extremism. However, de Maiziere said that many lines of investigation were being pursued.

According to reports, police have managed to identify only seven bodies so far. Lukasz Urban, a Polish driver, was found inside the lorry with a single gunshot wound to his head Investigators are yet to locate the gun. Among the missing are an Israeli woman visiting Berlin and an Italian woman who lived in the city , Telegraph reports.

German Chancellor Angela Merkel, who is facing intense pressure from her allies and opponents alike, for her open door refugee policy denounced the attack and said that it would be abhorrent if the individual turned out to be a person seeking asylum in Germany.

The right-wing Alternative for Germany (AfD) said that Germany was no longer a safe place. Frauke Petry, the leader of the party blamed Merkel of "importing terror to Germany over the past one and a half years."

Berlin truck crash
Police stand in front of the truck which ploughed last night into a crowded Christmas market in Berlin Hannibal Hanschke/Reuters