"A person in acute risk for suicidal behavior most often will show:
Warning Signs of Acute Risk:
Threatening to hurt or kill him or herself, or talking of wanting to hurt or kill him/herself; and or,
Looking for ways to kill him/herself by seeking access to firearms, available pills, or other means; and/or,
Talking or writing about death, dying or suicide, when these actions are out of the ordinary"

In this article from Suicidology, you will learn about warning signs