"Action will be taken against those guilty and all possible help would be extended to the bereaved family," Yadav told reporters here in a reply to a question.
He said that if laxity was detected on the part of any government or police official, then action would also be taken against them.
The 17-year-old girl, who was set on fire by Arjun in Luharra village in the district on Monday, died at the Aligarh Medical College last night, SP, Hathras, Happy Guptan said.
Later, the accused was arrested on the intervening night of Tuesday and Wednesday, Guptan said.
The girl, who sustained almost 90 per cent burn injuries, was rushed to the district hospital from where she was referred to Aligarh Medical College in a serious condition, police said.
The girl's father Ashok Kumar Sharma also sustained burn injuries in a bid to save his daughter, he said.
Arjun was named by the girl in her statement before a magistrate at the hospital.
According to the complaint lodged by the victim's father, the accused had been stalking the girl for some time due to which she had stopped going to the college, the SP added.
