Police in the US state of Texas are negotiating with a man who appears to have taken hostages at a synagogue in the town of Colleyville.
It is not known if he is armed or if anyone has been hurt.
The service was being streamed live when the incident started. The feed has since been taken down, but not before an angry man could be heard saying he didn't want anyone to be hurt.
Police have deployed special weapons teams to the scene.
It is unclear how many people are inside the building. Local residents are being evacuated.
The police department in Colleyville said in a tweet at 11:30 (16:30 GMT) that it was "conducting SWAT operations" at the address of the Congregation Beth Israel.
Two hours later the department said the situation "remains ongoing".
"We ask that you continue to avoid the area. We will continue to provide updates via social media," it said
