The man accidentally shot dead during the Manchester synagogue attack was holding the doors shut to make sure the knifeman could not enter, says rabbi Daniel Walker.
Police revealed earlier that one of the two victims died from a police bullet, fired as officers shot dead Jihad al Shamie.
Rabbi Walker told Sky News: "One of the men was murdered entering into the synagogue from the outside on his way to pray, he was coming for morning services, Yom Kippur, and his life was taken.
"The other man was inside the foyer, helping hold the doors to stop the terrorist coming in and when shots were fired he was fatally wounded.
"That was Adrian, who was holding the doors to make sure everyone inside stayed safe."
Adrian Daulby's family have described the 53-year-old a "hero" and a "down-to-earth man" who would "forever be remembered for his heroic act".
Attack latest: Al Shamie was on bail for alleged rape, Sky understands
Melvin Cravitz, 66, was the other man murdered in the attack in Crumpsall yesterday.
Rabbi Walker said the "pain is very raw - we are still in the crisis stage - but we are strong and we are going to recover".
"I still believe in hope, I still believe that we will come together and that we are better than this - and that we'll be better than this," he told Sky News.
He said the response from the public and politicians had been "heartening" and "it's good to know we're not alone".
Greater Manchester's police chief said one of the other three people in hospital also suffered a gunshot injury that isn't life-threatening
He said Mr Daulby's wound appeared to be a "tragic and unforeseen consequence of the urgently required action taken by my officers to bring this vicious attack to an end".