Berlin attack
A woman prays next to lit candles at the Christmas market where a truck plowed into the crowd in Berlin, Dec. 20, 2016. REUTERS/FABRIZIO BENSCH

UPDATE: 05:50 a.m. EST — German authorities are looking for a Tunisian man named Anis A in relation to Monday’s attack, when a truck plowed through a crowded Christmas market in central Berlin killing at least 12 people, based on an identity card found in the vehicle, German media reported.

Investigators said Wednesday more than one person may be involved and that they are possibly still armed. Another suspect was detained Wednesday but was shortly released.

“No one will rest until the perpetrator or perpetrators have been caught,” Interior Minister Thomas de Maizière reportedly said. The police said they have identified over 500 leads that would help them catch the attacker.

Meanwhile, German tabloid Bild reported Wednesday that one of the victims of the attack, the truck’s registered driver Łukasz Urban, likely put up a struggle and was shot only after the truck came to a halt about 50 yards into the market. The tabloid, citing anonymous sources part of the ongoing investigation, said Urban probably tried to grab the wheel to prevent further killings. “There must have been a struggle,” a source told Bild.

Original story:

The driver of the truck, which plowed through a crowded Christmas market in central Berlin on Monday killing at least 12 people, is still at large. German officials detained a Pakistani asylum-seeker Monday night but later released him saying they had the wrong man.

“We need to work on the assumption that an armed perpetrator is still on the loose,” Holger Münch, the head of the federal criminal police office, reportedly said. “We are on high alert and are investigating every possible angle.”

The Islamic State terrorist group, also called ISIS, claimed responsibility for the attack that also left 48 people injured. The group released a statement on the ISIS-affiliated Amaq news agency calling the attacker a “soldier of the Islamic State.”

German authorities are investigating the crash as a deliberate terror attack. Monday’s attack involved a tractor trailer speeding through a popular market outside the Kaiser Wilhelm Memorial Church in Breitscheidplatz, in the western part of central Berlin, at around 8 p.m. (2 p.m. EST).

The attack bears a striking resemblance to the July attack in the city of Nice in France where a Tunisian-born man barreled through a crowded beachfront in the city on Bastille Day, killing 86 people.

Meanwhile, hundreds of people attended a service held at the site of the attack in memory of the victims. In attendance were leading German officials, including Chancellor Angela Merkel and Interior Minister Thomas de Maizière. A group of 60 to 70 members belonging to the local mosque were also present.

“We wanted to show our solidarity and that our community stands for peace,” Hasnen Ahmad, a member of the group, reportedly said.

Berlin Christmas market attack
Parts of a Christmas market decoration stick in the windscreen of a truck following an accident with the truck on Breitscheidplatz square near the fashionable Kurfuerstendamm avenue in the west of Berlin, Dec. 19, 2016. REUTERS/FABRIZIO BENSCH

Merkel released a short statement Tuesday condemning the attack. She said it would be “particularly repugnant” if the attacker was an asylum-seeker given the “many many Germans who have dedicated themselves day after day to helping refugees, and in the face of the many people who actually need our protection and try to integrate into our country.”

Maizière, in a press conference Tuesday, said 18 people were “very seriously injured” in the Monday attack. However, he urged Germans to not “compromise our lifestyle, if we do that the enemies of freedom have already won. We are deeply saddened but we also fight for our freedom.”

Authorities put together a timeline of events as they unfolded, based on the information they had acquired. The attacker hijacked the truck, which belonged to a Polish company and was fitted with Polish license plates, that was on its way to Berlin. He shot the truck’s driver and left the body in the truck.

The attacker sped past Berlin’s zoo station, reaching the Christmas market at about 8 p.m. Monday. A witness told CNN the truck was travelling at 50 miles per hour. After speeding through for about 50 yards, the truck came to a halt after it struck a wooden structure. The attacker fled from the scene, reports said.

Meanwhile, the attack has intensified pressure on Merkel whose open door policy allowed nearly 890,000 asylum-seekers to enter the country last year. The anti-immigration, far-right Alternative for Germany (AfD) party accused Merkel of “importing terror to Germany over the past one and a half years.”

In the U.S., President-elect Donald Trump called the crash an act of terrorism, adding “the civilized world must change thinking” when it comes to such attacks.

The U.S. Department of State Bureau of Consular Affairs urged Americans in Berlin to inform their families of their safety and to stay away from the site of the attack.