He added that more than 200 people had suffered injuries.
"We have five people killed and more than 200 injured, with many seriously injured," Haseloff told a press conference at the scene of the attack.
On Friday evening, Germany's media reported that a car had rammed into a crowd at a Christmas market in Magdeburg. Saxony-Anhalt Minister-President Reiner Haseloff said earlier on Saturday that two people had died, one of whom was a small child. Police suspect that the driver was a 50-year-old Saudi man acting alone.
The local newspaper reported that the suspect had been recognized as a refugee in July 2016 and had a residence permit in Germany.