"Suicide is a permanent solution to a temporary problem". There is much wisdom to this sentence, and it is probably the best advice you can give a depressed person. Unfortunately, during that critical stage is difficult for them to visualise the temporary nature of the problem, and suicide is not uncommon. If you a have a friend or a loved one going through that stage of a depression, do take the possibility seriously and do what you can to prevent it from happening. In particular, make sure they are being handled by a competent professional. Fortunately, especially if people are young, this stage will not last very long, typically just a few days or weeks.