If you walk into what seems to be a suicide attempt, the first thing to manage is your own shock. Positive, active, immediate interventions are essential.
Get medical support if needed. Assess the degree of suicidality and maintain a safe area possible.

Don’t be afraid to ask direct questions and stay with the client until their risk has decreased or they are with someone else safe. Occupy the person and try to remove them from the location you found them in.