At what age is criminally responsible for a crime?

(Baonghean.vn) - Ms. Nguyen Thi X, residing in Yen Thanh district, stated: she has a daughter named N, born in 2013. During the summer vacation, she often goes to her neighbor's house to play. A week ago, the neighbor's son, T, born in 2003 (12 years old), seduced N into playing adult games. While T was playing adult games with N, N's brother discovered it and screamed, then went home to inform the family. The family reported T's actions to the competent authorities. After that, she took N to hospital P for examination, the doctor concluded that N had genital injuries. Ms. X wondered how to handle this case and whether T would be held criminally responsible.