BERLIN — The Berlin police said early Tuesday that the killing of at least 12 people and the wounding of dozens more when a truck plowed through a Christmas market on Monday night was “a suspected terrorist attack.”

In a statement, the police added that they were working swiftly and with “necessary care” in the investigation.

The truck jumped the sidewalk about 8 p.m. near the Kaiser Wilhelm Memorial Church, whose jagged spire, a reminder of the bombings during World War II, is one of the most symbolic sites in Berlin.