Essential training NEEDED for NHS agency staff!

So I've been on a psychiatric ward for a week and currently on constant observations. I walked into the bathroom today where a girl was laid in bath with water covering her head. She was fully clothed and clearly not well. The member of staff I was with didn't react in any way, she stood there blocking the door to the bathroom. I had to push passed her to get the plug out and hold her head above the water. It wasn't only after another patient saw what had happenedand was panicking that alerting other members of staff. They then pulled their alarm and attended to the girl as usual. I have voiced my concerns but unfortunately the staff member who was with me at the time was agency staff and many hospitals rely on them. Dont get me wrong, there's nothing wrong with agency staff but when it's supposed to be a safe environment where lives are at high risk then surely these people need to be trained so they are competent. I believe that more training is vital to to the people who are obviously needed extensively. When they do a shift on the job, they get 10 minutes then thrown in the deep end. Do you think this is adequate for the environment they are working in!!