"Today is a day of shame and disgrace," German President Frank-Walter Steinmeier said on a visit to the synagogue on Thursday.
"It fills us all with horror that an attack took place in our country, a country with this history, on a full synagogue on the highest Jewish day of celebration."
Questions have been raised about the police response after members of the Halle community said it took more than ten minutes for officers to arrive and that the gunman was held back only by the security door.
“It is scandalous that the synagogue in Halle is not protected by police on a holiday like Yom Kippur,” Josef Schuster, the head of the Central Council of Jews in Germany, told AFP.
“This negligence has now been bitterly repaid.”
The brutality of the assault “goes beyond anything we have seen in Germany in recent years and is absolutely shocking to every Jew in this country,” he added.
German President Frank-Walter Steinmeier and Interior Minister Horst Seehofer were among those due to visit Halle later on Thursday.
Halle community leader Max Privorozki confirmed the door was all that protected the synagogue where more than 50 worshippers were gathered for Yom Kippur prayers.
“I thought, that door will not hold,” he said.
Photographs from the scene on Thursday clearly showed bullet holes in the synagogue's wooden security door.
Marie van der Zyl, president of the Board of Deputies of British Jews, said Wednesday's attack was “an appalling far-right motivated murder perpetrated on Yom Kippur, the holiest day of the year for Jews, against innocent worshippers as well as diners in a kebab restaurant.”
Francis Kalifat, leader of the French community organisation Crif, said it demonstrated extremists “are a threat to our democracy and our way of life”.
Chief Rabbi Pinchas Goldschmidt, president of the Conference of European Rabbis, said it should be “a wake-up call for all those who follow the extreme right in Germany and across Europe.”
The shooter livestreamed his attack online. In the footage, reviewed by the JC, he says the Holocaust did not happen, blames "feminism" for falling birth rates and says Jewish people are "the root of all problems".
