<font color="#000088"> I know you did the right thing,even though it feels scary now that you haven't heard from him yet.It may mean that he's getting help,just try to think positive and wait to hear from him.
It took a lot of courage to do what you did, and I respect you for that.I had a similar situation where a friend of mine told me she was suicidal,and she was asking me where the arteries were in her neck,and similar questions that led me to believe she was serious.So as soon as I got done talking to her I called her Doctor,which was also a good friend to her,knowing that she would be able to calm her down,but if not she had the authority to put her in the hospital involuntarily if necessary.
Later that night,that friend called back,and told me she felt better,and thanked me for calling her Doctor/friend to help her!

So don't give up,your friend may call after some time and tell you he was getting help. The police won't tell where they got thier information from,at least thier not supposed to.But if your friend is in the hospital getting treatment,it may take some time in thier before he/she would be able to contact you.
So just be patient, and give it some time, but keep reminding yourself that you may have saved this friends life! </font>