Two men killed in an attack on a synagogue in Manchester have been named by police as Adrian Daulby, 53, and Melvin Cravitz, 66.
Three others remain in hospital with serious injuries after Jihad Al-Shamie rammed a car into people before stabbing others on Thursday morning.
The attack, which police have said was a terrorist incident, came on Yom Kippur, the holiest day in the Jewish religious calendar.
The attacker, who was shot dead at the scene, was a 35-year-old British citizen of Syrian descent who was not previously known to counter terrorism police, the home secretary told the BBC.
"Right now our hearts are shattered," UK's Chief Rabbi, Sir Ephraim Mirvis, told the BBC.
Speaking to Radio 4's Today programme, he said: "What transpired yesterday was an awful blow to us, something which actually we were fearing might happen because of the build up to this action."
The attack was not only "a very dark time" for Jews in Britain "but for all of our society", he said.
"Our responsibility is to make sure our Jewish community, our citizens can go about their lives with safety and security," Home Secretary Shabana Mahmood told the BBC.
"I do not want Jewish people in our country to feel like they have to live a smaller Jewish life, that they cannot go about their business and practice their faith and go to their communal institutions in freedom," she said.
Al-Shamie was not known to counter-terrorism police, she told BBC Breakfast, and it was "too early" to say if there was a terrorist cell behind the attack.
The police investigation was "continuing at pace" and there was an increased police presence at synagogues across the UK.
"The government does provide funding for security," Mahmood said, adding: "I think we will have to consider what more we can do to deal with rising antisemitism.
Greater Manchester police said it was supporting the families of the two men killed.
"My deepest sympathies are with Mr Daulby and Mr Cravitz's loved ones at this extremely hard time," Det Ch Supt Lewis Hughes said.
He said trained family liaison officers were in contact with them and would continue to support them through the coronial process.
"Whilst there are processes which must be followed, we commit to being mindful of cultural preferences and sensitivities and to ensuring that these men and their loved ones' wishes are respected," he said, adding that the two men were from Crumpsall.
Post-mortems are taking place on Friday, the Home Office said.
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