SACRAMENTO, Calif. (KTXL/AP) — Sacramento police officials said they are monitoring a hostage situation in Texas and will increase patrols at synagogues within the city.

A man took hostages Saturday during services at a Texas synagogue where he could be heard ranting in a livestream and demanding the release of a Pakistani neuroscientist who was convicted of trying to kill U.S. Army officers in Afghanistan.

At least four hostages were initially believed to be inside the synagogue, according to three law enforcement officials who were not authorized to discuss the ongoing investigation and who spoke to The Associated Press on the condition of anonymity. The synagogue’s rabbi was believed to be among the hostages, one of the officials said. One of the officials said the man claimed to be armed but authorities had not confirmed whether he is.

“The Sacramento Police Department is aware of and closely monitoring the hostage situation taking place in Colleyville, TX. While there are no known threats In our city, out of an abundance of caution, @SacPolice will be increasing our patrols at Synagogues within Sacramento,” Sacramento police officials posted on Twitter Saturday evening.

The Colleyville Police Department said one hostage was released uninjured shortly after 5 p.m. Saturday. The man was expected to be reunited with his family and did not require medical attention. A law enforcement official said the hostage who was released was not the rabbi.

Authorities are still trying to discern a precise motive for the attack. The hostage-taker was heard demanding the release of Aafia Siddiqui, the Pakistani neuroscientist suspected of having ties to al-Qaida, the officials said. He also said he wanted to be able to speak with her, according to the officials. Siddiqui is in federal prison in Texas.

The officials said investigators have not positively identified the man and cautioned that the information was based on a preliminary investigation as the situation was still rapidly developing.