The man believed to have driven a truck into a crowded Christmas market in Berlin Monday evening had come to Germany as a refugee from Pakistan this past February, multiple German media outlets reported.

The attack killed at least 12 people and left 48 others injured. Officials in Germany and the United States have described the crash as an apparent terror attack, though no group has claimed responsibility.

If confirmed, the revelations are likely to heap more pressure onto German Chancellor Angela Merkel, whose decision to accept waves of migrants from Africa and the Middle East has stoked controversy and unsettled Germany and Europe.

Der Tagesspiegel reported that the suspect, whom the paper said was Afghan or Pakistani, was known to police for multiple minor offenses, but had not made the radar of anti-terror authorities. The dpa press agency reported that the suspect used multiple names, making it difficult for authorities to confirm his actual identity.

The suspect was arrested about 1 1/2 miles away from the scene of the carnage at the popopular Christmas market outside the Kaiser Wilhelm Memorial Church. A Polish passenger in the truck died at the scene as paramedics attended to him.

Several questions remained unanswered early Tuesday, including exactly how the suspect came to be behind the wheel of the large Scania truck with a Polish license plate that was carrying several tons of steel.

The truck was registered in Poland, and police said it was believed to be stolen from a building site there. They didn't give a specific location.

The Polish owner of the truck said he feared the vehicle, driven by his cousin, may have been hijacked. Ariel Zurawski said he last spoke with the driver around noon, and the driver told him he was in Berlin and scheduled to unload Tuesday morning. "

Die Welt newspaper reported that the truck was driven into the market crowd without its headlights on, another indication that the crash was deliberately planned.

Berlin police spokesman Winfried Wenzel told the paper that after the truck came to a stop, the suspect fled in the direction of Berlin's famous Tiergarten park. A witness followed the suspect and pointed him out to police, who arrested him near the Victory Column monument.

In total, Wenzel said the witness who alerted police followed the suspect for almost a mile and a quarter through the streets of the German capital.

"He probably wanted to find shelter in the darkness of the park," Wenzel told Die Welt.

The Associated Press contributed to this report.