Authorities in Colleyville, a city of about 26,000 in northeastern Texas, are negotiating with a man who has reportedly taken people hostage at a synagogue during Saturday services, US media reported.

Colleyville police said they were conducting SWAT operations. Residents in the area were being evacuated, police said.

Around two hours after police first reported the incident, they said the situation was still ongoing.

What is going on at Congregation Beth Israel synagogue in Colleyville?

A police officer was quoted as saying by the daily Dallas Morning News that it was unclear how many people are inside the building or whether anyone was armed.

The paper reported, citing police, that negotiators have made contact with somebody inside the synagogue who "they believe is a suspect."

The Fort Worth Star-Telegram newspaper said the service at the Congregation Beth Israel synagogue was being live-streamed on Facebook, but the video was taken down. It said "muffled audio of what sounded like negotiations with police" could be heard.

According to the Fort Worth Star-Telegram, the man mentioned his sister and Islam, used profanities and repeatedly said he thought he was going to die. Reuters news agency said the livestream cut off at around 2000 UTC.

The suspect took the synagogue's rabbi and three others hostage, according to ABC News. The man claims to be the brother of Aafia Siddiqui, who was convicted of attempting to kill US military personnel in Afghanistan and is serving an 86-year prison sentence at a prison in Fort Worth.

Shortly before the feed cut out, the man said, "You got to do something. I don't want to see this guy dead," according to the AP news agency.

US broadcaster NBC News reports, "The hostage taker at the synagogue in Texas had the rabbi call a different rabbi in New York City. The purpose of the call was to again demand the release of Aafia Siddiqui."

NBC News added, "The NYPD has deployed its counter-terrorism teams to the synagogue where the rabbi who received the call in New York out of an abundance of caution."

What reactions have there been to events in Texas?

Dallas mayor Eric Johnson tweeted Dallas police are "deploying additonal patrols to Dallas synagogues and other sites."

White House spokeswoman Jen Psaki wrote US President Joe Biden "has been briefed about the developing hostage situation" and added, "Senior members of the national security team are also in touch with federal law enforcement leadership."

Israeli Prime Minister Naftali Bennett wrote on Twittter that he is "closely monitoring the hostage situation."

"We pray for the safety of the hostages and rescuers," Bennett wrote.