Live Stream! Berlin Attack & Merkel Policies: LIVE Debate (Mo Ansar vs Maximilian Krah)

The suspect in custody, said German Interior Minster Thomas de Maizière, was a Pakistani asylum-seeker detained late Monday. The man denied any involvement in the assault that left the festive market wood-splintered and bloodstained, authorities said.

Berlin Police Chief Klaus Kandt, however, warned that it was “uncertain” if the man in custody was the perpetrator, and authorities asked the public to “stay alert.” Germany’s general prosecutor added: “We need to consider that he was not the perpetrator.”

The statements raised the alarming prospect that the assailant — who killed 12 and left 52 injured — might still be at large.

The 12 victims included a Polish national shot dead and found in the passenger seat of the massive black truck that careened into the crowded market. The truck had Polish plates, and the original driver was en route to Berlin with a cargo of 25 tons of steel. German media have speculated that the vehicle may have been hijacked and the driver killed.

Two senior German officials briefed on the matter had earlier told The Washington Post that man detained was a Pakistani asylum seeker.