Four hostages held by a gunman at Beth Israel Reform synagogue in Colleyville, Texas, were freed safe and sound on Saturday night, Governor Greg Abbott announced.

"Prayers answered. All hostages are out alive and safe," he tweeted.

Colleyville Police also confirmed that the hostages had been freed.

"The SWAT situation in Colleyville is resolved and all hostages are safe. We continue to work in partnership with the FBI to finalize all details," it tweeted.

In a subsequent press conference, the chief of police confirmed the gunman was killed.

Israel's Ambassador to the US, Mike Herzog, welcomed the end of the hostage crisis.

"Grateful that the hostages held at Congregation Beth Israel in Colleyville, TX, were rescued and returned to their loved ones. This horrific incident is a reminder that the threat of antisemitism is ever present. Jews should not be afraid to pray in their synagogues," he wrote.

"Thank you to all the local and federal law enforcement and first responders who were on the scene and helped prevent a tragedy this Shabbat. We will continue to stand with the Texas Jewish community and against every form of hatred," added Herzog.

Israel's Ambassador to the UN, Gilad Erdan, welcomed the end of the hostage crisis.

"Thank God all the hostages at Cong. Beth Israel are safe. I am thankful for the law enforcement who responded swiftly to ensure their safety," he tweeted.

"This horrific incident reminds us that US leaders must act today. Disaster awaits if serious action is not taken against antisemitism," he added.

US President Joe Biden welcomed the conclusion of the hostage crisis.

"Thanks to the courageous work of state, local and federal law enforcement, four Americans who were held hostage at a Texas synagogue will soon be home with their families. I am grateful to the tireless work of law enforcement at all levels who acted cooperatively and fearlessly to rescue the hostages. We are sending love and strength to the members of Congregation Beth Israel, Colleyville, and the Jewish community," he said.

"There is more we will learn in the days ahead about the motivations of the hostage taker. But let me be clear to anyone who intends to spread hate—we will stand against anti-Semitism and against the rise of extremism in this country. That is who we are, and tonight, the men and women of law enforcement made us all proud," added Biden.

The Beth Israel Synagogue is led by Rabbi Charlie Cytron-Walker, who was also reportedly one of the hostages.

Reuters reported earlier that police were negotiating with a man believed to have taken people hostage at the synagogue during Shabbat services.

Shortly after 2:30 a.m. Israel time (6:30 p.m. local time), police said that one of the hostages was freed, unharmed.

At around 5:30 a.m. Israel time (9:30 p.m.) local time, a CNN team in Colleyville heard a loud bang, followed by a short blast of rapid gunfire coming from the direction of the synagogue. Shortly afterwards, Abbott tweeted that the remaining hostages were freed.

The Colleyville Police Department said it had evacuated residents from the area around the Congregation Beth Israel as it deployed SWAT teams, the report said.

On Twitter, police said that they were "conducting SWAT operations" on the synagogue's block.

"The situation at the 6100 block of Pleasant Run Road posted about earlier remains ongoing. We ask that you continue to avoid the area. We will continue to provide updates via social media," Colleyville Police tweeted.

An earlier tweet by Colleyville Police had read: "We are currently conducting SWAT operations around the 6100 block of Pleasant Run Rd. All residents in the immediate area are being evacuated. Please avoid the area."

It is not clear if anyone was injured, nor how many people were in the synagogue at the time of the incident.

The service was being livestreamed on Facebook when the incident occurred, and the recording captured what seems to be negotiations with police. After a few hours of the livestream capturing the incident, the streaming was abruptly ended and the video removed from the Beth Israel's Facebook page. The video which recorded the streaming of the synagogue's evening service, just 18 hours prior, is still visible.

According to FBI Dallas spokeswoman Katie Chaumont, police were first called to the synagogue around 11 a.m. and people were evacuated from the surrounding neighborhood soon after that.

CNN quoted Colleyville Police Sgt Dara Nelson as saying that the FBI and Texas Department of Public Safety are assisting a hostage situation at the Congregation Beth Israel in Colleyville, Texas.

Nelson said that "there are no injuries at this time," CNN added. "The FBI negotiators are the ones who have contact with the person in the building."

Nelson also said that at this time, "There is “no threat to the general public."

The Star-Telegram added that the man has reportedly mentioned both his sister and Islam. Later, it added that "the man has said a few times he didn’t want anyone hurt, and he has mentioned his children. He also said repeatedly he believes he is going to die."

According to a later report, the gunman said that he is Muslim and is holding at least six people hostage.

He emphasized that "he will kill people if anyone gets close to the synagogue."

The Telegraph reported that the suspect has an English accent.

Meanwhile, the gunman himself claims to be the brother of Aafia Siddiqui, a Pakistani woman who was sentenced to 86 years in prison after she tried to murder American soldiers in 2008. It is her release which he reportedly is demanding in exchange for the hostages.

However, the Siddiqui family lawyer told ABC that the gunman is not her brother, and that her brother and the family are working to bring about her release in peaceful ways.

The gunman also claimed to have planted bombs on the premises.

A source at the scene told ABC News that the suspect took the rabbi and three others hostages, and that there are bombs in unknown locations. That source also confirmed to ABC that Siddiqui is the gunman's sister and that he took the hostages in order to free her.

However, according to the Star-Telegram, the US government has refused to trade her for American hostages multiple times, including for journalist James Foley prior to his execution by ISIS.

Reports claimed that the suspect had no anti-Semitic motives, and was instead driven by an "unbalanced emotional state."