The bloodiest attack of its sort in years claimed seven lives and left at least three more wounded.
Outside the Old City, two more persons were attacked and injured on Saturday.
The shooter in Saturday’s incident, according to Israeli authorities, was a 13-year-old kid.
They stated he was “neutralised,” but they didn’t elaborate.
The Silwan neighbourhood was targeted; it is located on the outskirts of the Old City of Jerusalem. A father and kid were hurt and are in “moderate to critical condition,” according to the police.
In the wake of the two assaults, counter-terrorism personnel have been stationed in the Jerusalem region “permanently” to “rapidly respond to unusual circumstances if necessary.”
Police called the individual who assaulted the synagogue on Friday a “terrorist,” and local media confirmed that he was a Palestinian from East Jerusalem.
Israeli police commissioner Kobi Shabtai said at the scene of the incident on Friday that it was “one of the deadliest attacks we have experienced in recent years.”
At approximately 20:15 local time, a shooter opened fire on Israeli worshippers as they were leaving a synagogue in the city’s Neve Yaakov neighbourhood after praying to mark the beginning of the Jewish Sabbath (18:15 GMT).
After that, authorities reportedly shot and killed him.
Palestinian extremist organisations have hailed the incident, but none have claimed responsibility for it.
High tensions have persisted since Thursday, when an Israeli military incursion in Jenin, in the occupied West Bank, resulted in the deaths of nine Palestinians.
As a result, rockets were fired into Israel from Gaza, prompting an Israeli air attack in retaliation.
Premier of Israel, Benjamin Netanyahu
The Israeli Prime Minister, Benjamin Netanyahu, went to the location of the incident on Friday.
The massacre at the synagogue occurred on Holocaust Memorial Day, which honours the six million Jews and other victims of the Nazi genocide.
James Cleverly, the foreign secretary of the United Kingdom, tweeted: “Attacking a synagogue on Holocaust Remembrance Day, and on Shabbat, is despicable. To our Israeli friends, we say,”
According to the White House, Vice President Joe Biden called Israeli Prime Minister Benjamin Netanyahu and offered “proper methods of support.”
Mr Netanyahu and the divisive far-right National Security Minister Itamar Ben-Gvir both attended the scene of the crime soon after it occurred.
On Saturday, an Israeli military spokeswoman confirmed that Israeli soldiers were being increased in the occupied West Bank.
According to BBC Jerusalem correspondent Yolande Knell, there is growing frustration at Mr Ben-Gvir for failing to restore public safety in Israel.
Israeli police cordon off the scene of an alleged assault on a synagogue
On Friday, Israeli security agents and first responders rushed to the site of a gunshot.
A UN spokesman expressed Secretary-General Antonio Guterres’ “grave concern” at the “current escalation of violence in Israel and the occupied Palestinian territories.
Stephane Dujarric remarked, “Now is the time to practise maximum restraint.”
Since the 1967 Middle East War, Israel has occupied East Jerusalem and claimed the entire city for itself as its capital. This claim is not recognised by the great majority of countries.
The Palestinians envision East Jerusalem as the capital of their future state.