'The Stuff Kids Say' is a new six week TV ad campaign launched by the NSPCC that urges people not to wait until they're certain to report sexual abuse.
According to the NSPCC, half of people who contact its helpline have waited over a month to get in touch.
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The US president is seeking an investigation by the Justice Department.
The casualty was taken into the care of paramedics with a suspected leg injury.
The 16-year-old was discovered with stab wounds on Thursday afternoon.