MAGDEBURG, Germany — Germans on Saturday mourned both the victims and their shaken sense of security after a Saudi doctor intentionally drove into a Christmas market teeming with holiday shoppers, killing at least five people, including a small child, and wounding at least 200 others.

Authorities arrested a 50-year-old man at the site of the attack at Magdeburg on Friday evening and took him into custody for questioning. He has lived in Germany since 2006, practicing medicine at Bernburg, about 25 miles south of Magdeburg. officials said.

The state governor, Reiner Haseloff, told reporters that the death toll rose to five from a previous figure of two and that more than 200 people in total were injured.

Chancellor Scholz said that nearly 40 of them “are so seriously injured that we must be very worried about them.”

The German press identified the suspect as Taleb A., withholding his last name in line with privacy laws, and reported that he was a specialist in psychiatry and psychotherapy.

Mourners lit candles and placed flowers outside a church near the market on the cold and gloomy day. Several people stopped and cried. A Berlin church choir whose members witnessed a previous Christmas market attack in 2016 sang “Amazing Grace,” offering their prayers and solidarity with the victims.

The man behind the attack
There were still no answers Saturday as to what motivated the man to drive his black BMW into a crowd in the eastern German city.

The suspect, describing himself as a former Muslim, shared dozens of tweets and retweets daily focusing on anti-Islam themes, criticizing the religion and congratulating Muslims who left the faith.

He also accused German authorities of failing to do enough to combat what he said was the “Islamism of Europe.” Some described him as an activist who helped Saudi women flee their homeland. He has also voiced support for the far-right and anti-immigrant Alternative for Germany party.

Mr. Haseloff said Friday that authorities believed the man acted alone.

Magdeburg is still shaken
The violence shocked Germany and the city, bringing its mayor to the verge of tears and marring a festive event that’s part of a centuries-old German tradition. It prompted several other German towns to cancel their weekend Christmas markets as a precaution and out of solidarity with Magdeburg’s loss. Berlin kept its markets open but has increased its police presence at them.

Germany has suffered a string of extremist attacks in recent years, including a knife attack that killed three people and wounded eight at a festival at the western city of Solingen in August.

Magdeburg is a city of about 240,000 people, west of Berlin, that serves as Saxony-Anhalt’s capital. Friday’s attack came eight years after an Islamic extremist drove a truck into a crowded Christmas market in Berlin, killing 13 people and injuring many others. The attacker was killed days later in a shootout in Italy.

Mr. Scholz and the interior minister, Nancy Faeser, traveled to Magdeburg on Saturday, and a memorial service is to take place in the city cathedral in the evening. Ms. Faeser ordered flags lowered to half-staff at federal buildings across the country.

The market itself was still cordoned off Saturday with red-and-white tape and police vans every 50 yards. Police guarded every entry to the market. Some thermal security blankets still lay on the street.

Christmas markets are a German holiday tradition cherished since the Middle Ages, now successfully exported to much of the Western world.