Police came to my mom’s house — hands on their guns

As the title says, the police showed up at my mom’s house about an hour ago with their hands on their guns looking for my 21 year old brother. They wouldn’t give her any information except that it was a welfare check that was called in anonymously. My brother doesn’t live with my mom so the police did not find him.

He is a drug addict and has been experiencing some metal health issues within the last few months. He doesn’t have a diagnosis but he hears voices and believes people are trying to steal his memories. (Yes I’ve tried to get him help :-/)

What could this possibly be about. His phone is off and my mind is going crazy. I’m so worried. Did he threaten someone ? Did he threaten himself ?