Do not ignore these signs. You will not be giving them new ideas. Do not act surprised or shocked. This will make them withdraw from you. Continue talking and ask how you can help.
Offer hope that alternatives are available.
Do not offer glib reassurance. It may make the person believe that you do not understand. Show interest and support. If you cannot do this, find someone who can, such as a neighbor or a minister, priest, or rabbi. Ask whether there are guns in the house.