The news heightened fears of more antisemitic violence in a nation still scarred by the Holocaust and witnessing the rise of the right-wing Alternative for Germany (AfD) party.
"It's very scary," said Samuel Tsarfati, a 27-year-old stage director, as he left a Berlin synagogue with fellow French national Samuel Laufer.
The pair, who live and work in the German capital, had spent the holiest day in the Jewish calendar secluded in prayer and switched off their mobile phones for 25 hours of fasting.
Other members of Germany's 200,000-strong Jewish community expressed similar alarm over the attack. After trying to blast into the Halle synogogue, a lone suspect killed a woman outside and a man in a nearby kebab shop.
"It's not a coincidence it happened in east Germany. The far-right AfD is very strong there," Tsarfati said. Leaders of the AfD, which made big gains in elections in two eastern states last month, condemned Wednesday's attack in Halle.
Attacks on Jews rose by 20% last year and were mainly carried out by right-wing extremists. Even before the Halle shooting, a heavy police presence guarded the synagogue in the trendy suburb of Prenzlauer Berg where Tsarfati and Lauferis attended prayers.
Jews and German politicians have been particularly worried by comments by Bjoern Hoecke, the AfD leader of eastern Thuringia state, that the Holocaust memorial in Berlin is a "monument of shame" and that schools should highlight German suffering in World War Two.
"What happened today shows that the AfD should not be underestimated," said Laufer. "AfD leaders like Hoecke don't want to see that their words encourage some people to kill."
Hoecke was among the AfD leaders to condemn the Halle attack.
The Halle gunman broadcast antisemitic comments before he opened fire. Several German media outlets said he acted alone although police have not confirmed this.
The far-right AfD entered the national parliament for the first time two years ago, riding a wave of anger at Chancellor Angela Merkel's 2015 decision to welcome almost 1 million migrants. The party's rise has alarmed Jewish leaders who condemn the party's verbal attacks against Muslim migrants.
'BLINDED BY HATRED'
Charlotte Knobloch, a Holocaust survivor and president of the Jewish Community in Munich, suggested that the AfD's anti-immigrant rhetoric was contributing to an atmosphere of hate that encouraged political violence.
"This scary attack makes it clear how fast words can become acts of political extremism," she said in a statement. "I'd be interested to know what that AfD has to say about such excesses, for which it had prepared the ground with its uncultured hate and incitement."
At the gold-domed New Synagogue in Berlin's city center about 200 people, including Muslim leaders, held a vigil, some carrying Israeli flags and others holding candles. Merkel visited the synagogue in the evening and took part in prayers.
Renate Keller, a 76-year-old attending the vigil with her husband, said the attack in Halle showed that Germany was not doing enough to fight antisemitism.
"It scares me that after the Holocaust some people have learned nothing from our history, which still weighs on us today," she said. "People like the attacker have probably never met a Jew in their lives. They are just blinded by hatred."
Josef Schuster, president of the Central Council of Jews in Germany, warned of the incendiary potential far-right politics."It shows that right-wing extremism is not only some kind of political development, but that it is highly dangerous and exactly the kind of danger that we have always warned against."