The alleged attack Friday evening in Magdeburg, about 130 kilometers (80 miles) west of Berlin, killed a 9-year-old and four adults and injured 41 people badly enough that authorities warned the death toll could rise.
Magdeburg marked the tragedy Saturday with the tolling church bells at 7:04 p.m., the exact time of the attack in the city of roughly 240,000 people.
The driver, a 50-year-old doctor who immigrated from Saudi Arabia in 2006, surrendered to police at the scene. He's being investigated for five counts of suspected murder and 205 counts of suspected attempted murder, prosecutor Horst Walter Nopens said at a news conference.