What is known about the German Christmas market attack and its impact

A sea of flowers, soft toys and candles have been left in tribute to the victims outside the Johannis church close to the Christmas market (Ebrahim Noroozi/AP)

Four women and a nine-year-old boy were killed and 200 people were injured when a Saudi doctor allegedly drove into a Christmas market packed with people in the German city of Magdeburg on Friday night.

Here are the key details about what is known about the attack, what German authorities knew about the suspect, and what the incident may mean for elections in the country early next year.