All hostages were safely released from a Colleyville, Texas, synagogue after a twelve-hour standoff and the hostage-taker was killed, US officials announced on Sunday.

“The four hostages are unharmed, and the hostage-taking is not part of an ongoing threat,” the Dallas office of the US Federal Bureau of Investigation said. The hostages included a rabbi.

"Prayers answered. All hostages are out alive and safe," Texas Governor Greg Abbott tweeted about 20 minutes after a large bang and gunfire were heard in the direction of the synagogue.

The FBI said their “negotiators were in near-constant communication with the hostage-taker before a deliberate decision to breach the synagogue.”

Soon after these announcements, media outlets in the nearby cities of Fort Worth and Dallas reported that the hostage-taker, who earlier identified himself as Muhammad Siddiqui, was dead.

The man who raided the synagogue during the Sabbath services also claimed that he was Aafia Siddiqui’s brother and demanded her release.

Read more: Dr Aafia Siddiqui sustained 'minor injuries' in assault by fellow inmate in US prison: FO

Siddiqui, a Pakistani-American neuroscientist, was sentenced to 86 years in prison by a New York court in 2010 for the attempted murder of US officers in Afghanistan.

Dr Aafia has nothing to with the incident: attorney

However, the attorney who represents Dr Siddiqui said "she has absolutely no involvement with" the hostage-taking and the perpetrator was not Siddiqui's brother.

“She does not want any violence perpetrated against any human being, especially in her name," Marwa Elbially told CNN by phone. "It obviously has nothing to do with Dr Siddiqui or her family."

"Whoever the assailant is, we want him to know that his actions are condemned by Dr Siddiqui and her family," Elbially said. "We implore you to immediately release the hostages and turn yourself in."

The resolution came more than 12 hours after the suspect entered the Congregation Beth Israel as the synagogue was live-streaming its Sabbath morning service on Facebook.

The live stream appeared to capture part of the incident before it was removed. Law enforcement officials told CNN they reviewed the stream and used it to gather clues on the incident and the individuals involved.

Two law enforcement officials told CNN that investigators believe the perpetrator may have been motivated by a desire to release Dr Siddiqui.

At the suspect’s request, the rabbi of the congregation called a well-known rabbi in New York City. The alleged invader, who had no connection with the rabbi, told the priest that Dr Siddiqi was framed, and he wants her released, the officials said.

In a separate state, a US-based Muslim advocacy group known as CAIR, and Free Dr Aafia Movement condemned the hostage-taking and said that her brother had nothing to do with the incident.

John Floyd, who heads the Houston chapter of the Council on American-Islamic Relations (CAIR) and a legal counsel for Dr Siddiqui’s brother said: “This antisemitic attack against a house of worship is unacceptable. We stand in solidarity with the Jewish community.”

They also said that they wanted to “make it very well known that the hostage-taker is NOT Dr Aafia Siddiqui's brother, who is not even in the same region where this horrible incident took place. Dr Aafia Siddiqui and her family strongly condemn this act and do not stand by the perpetrator.

They said that Dr Siddiqui's family has always stood firm in advocating for the release of their sister from incarceration by legal and non-violent means only.

Before the media reported the suspect’s death, CAIR and the Dr Siddiqui family’s legal counsel urged him to “immediately release the hostages and turn yourself in.”

Biden condemns 'rise of extremism'

President Joe Biden pledged to “stand against anti-Semitism and against the rise of extremism in this country.” “I am grateful to the tireless work of law enforcement at all levels who acted cooperatively and fearlessly to rescue the hostages,” he said.

“We are sending love and strength to the members of Congregation Beth Israel, Colleyville, and the Jewish community.”

Israel's ambassador to the United States, Michael Herzog, said he was “grateful” all the hostages had been released safely.

“No one should ever be afraid to assemble in their place of worship,” the Jewish Community Relations Council said in a statement.