At least two were killed in the German city of Halle on Wednesday October 9th after "several shots" were fired at a synagogue as Jews celebrated the holy day of Yom Kippur.
One suspect was arrested with a larger ongoing search for other perpetrators; security was tightened in synagogues in other eastern German cities while Halle itself was in lockdown, AFP reported.
Police said on Twitter that "early indications show that two people were killed in Halle. Several shots were fired." Police urged residents in the area to stay indoors.
Police confirmed the "perpetrators fled in a car". One suspect has been caught.
"We saw through the camera of our synagogue that a heavily armed perpetrator wearing a steel helmet and rifle was trying to shoot open our door," Jewish community leader Max Privorotzki, who was in the Halle synagogue, told Stuttgarter Zeitung.
"The man looked like he was from the special forces. But our doors held firm," Privorotzki said, adding that there was also an attempt to shoot open the gate to the neighbouring Jewish cemetery.
"We barricaded our doors from inside and waited for the police," he said, adding that "in between, we carried on with our service."
Privorotzki said that between 70 and 80 people were in the synagogue as Jews around the world were marking one of the holiest days in the Jewish calendar. Two people were also seriously injured in the attack and were being operated on, a spokesman for the city's hospital said.
Speaking to NTV, a police spokesman said the motive of the suspect or suspects was not clear. "We don't have any indication about the motive of this act," he said.
Police confirmed that one of the casualties was killed after a hand grenade was thrown into a nearby kebab shop. The other victim is a woman, Welt reported.
The shooting took place in front of a synagogue in the Paulus district, and a hand grenade was also flung into a Jewish cemetery.
Anti-terrorist prosecutors confirmed that they were taking over the probe given "the particular importance of the case" which he said involved "violent acts that affect the domestic security of the Federal Republic of Germany".
Current suspicions appear to point to the far-right. "The evidence points to the possibility of a far-right background," a spokesman for federal prosecutors told Germany's evangelical news service.
An unauthenticated video circulating in German media showed a man wearing a helmet getting out of a car before firing several shots in the air.
"It is terrible news from Halle and I hope very much that the police will manage to catch the perpetrator or perpetrators as quickly as possible so that no other person will be in danger," Chancellor Angela Merkel's spokesman Steffen Seibert said.
"A shooting at Halle synagogue on Yom Kippur hits us all in the heart," said Heiko Maas, Germany's minister for foreign affairs.
Speaking to news channel NTV, eyewitness Konrad Roesler, said that he was in a Turkish restaurant about 600 metres away from the synagogue when "a man wearing a helmet and military uniform" flung a hand grenade at the store.
"The grenade hit the door and exploded," he said. "[The attacker] shot at least once in the shop, the man behind me must be dead. I hid in the toilet and locked the door."
This attack comes three months after the shocking assassination of pro-migrant politician Walter Luebcke in the western city of Kassel, allegedly by a neo-Nazi.
Luebcke's killing has seriously shaken the country, raising questions about whether it has failed to take a rising threat from right-wing extremists seriously.
Former communist states in East Germany have also gained notoriety for their far-right extremists. Last month, a neo-Nazi "terrorist" cell based in the eastern town of Chemnitz was put on trial for plotting a violent uprising in Germany.
Last month, Interior Minister Horst Seehofer warned of the rising danger of the militant far-right, saying that police had uncovered 1,091 weapons including firearms and explosives during probes of crimes linked to the far right last year.
Fears of a new terrorist attack were also revived on October 7th when a Syrian man hijacked a truck and smashed it into cars stopped at a traffic light in the city of Limburg, injuring several people.
Frankfurt prosecutors said that the 32-year-old has been remanded in custody, suspected of attempted murder and bodily harm as well as a traffic offence.
Germany has been on high alert following several attacks in recent years, including some claimed by Isis terrorist group, as well as neo-Nazi plots.