There's an argument that the big companies should be doing a lot more, said Justin Brookman, the director of consumer privacy and technology policy for Consumer Reports. "We worked with urgency to remove this content and will permanently suspend any accounts found to be posting or reposting content of this abhorrent act".
In one posted by German news outlet Terreur & Crime Nieuws, a young white man with a shaved head sitting in the driver's seat of a vehicle points the camera at himself and says, "Hi, my name is Anon, and I think the Holocaust never happened".
After not being able to open the door to the Synagogue after several attempts, the attacker got into his vehicle.
German Interior Minister Horst Seehofer called Wednesday's attack "a disgrace for our whole country" after he visited the current house of worship on Thursday. The incident near the synagogue comes on Yom Kippur, the holiest day in the Jewish calendar.
Appearing to improvise, he then shot dead a random woman in the street and a man inside a nearby kebab shop, before being captured by police. The suspect, 27-year-old German Stephan Balliet, filmed the assault and live-streamed it.
The attack in Halle, in which two people were killed outside the synagogue, has stoked renewed concern about rising far-right extremism and questions about the police response.
In that sense, Wednesday's shooting represents a tragic milestone for Western Europe, where growing radicalization among both neo-Nazis and Islamists is leading to what some scholars on anti-Semitism are calling a "perfect storm" - violent anti-Semitism stemming from both the right and the left.
Several hours later, they announced there was no longer an "acute" danger to the population and residents could go back into the streets.
Unlike synagogues in many other German cities, the one in Halle didn't have police officers outside for Yom Kippur, an omission strongly criticized by Jewish leaders. They didn't specify why the "acute" danger is now deemed to have passed.
Police in two other cities in eastern Germany, Dresden and Leipzig, stepped up security at synagogues there after the shooting in Halle.
Spokesman Hana Rubasova says officers are focusing on synagogues and other Jewish buildings and objects, Prague's global airport and the border. Two people were also wounded by bullets and underwent surgery.
A German security official, who spoke on situation of anonymity to discuss about an ongoing investigation, confirmed that the gunman had recorded the assault on a head camera.
One suspect was arrested but two other alleged gunmen fled in a hijacked auto after leaving two other people seriously wounded, authorities said. Prosecutors will have to sift through his communications and his activities on the darknet, a part of the internet hidden from public view.
"According to the federal prosecutors' office, there are enough indications that it was possibly a right-wing extremist motive".
A short time later, police reported the arrest.
Halle's central train station has also been closed, railway company Deutsche Bahn said.
The clip shown by regional public broadcaster MDR shows the man getting out of a auto and firing four shots from behind the vehicle from a long-barreled gun.
What he was shooting at wasn't clear. At least two other people were reportedly injured. "Please nonetheless remain vigilant".
"All our country's citizens of Jewish faith can be sure that we are with them with our whole heart and we will give them all the security that is possible", Vice Chancellor Olaf Scholz said.
Halle police confirmed that "multiple shots were fired" and that multiple suspects fled the scene in a auto.
The NYPD's Counter Terrorism unit are "closely monitoring" the shooting reports, they tweeted Wednesday morning.