Among the accused is a youth who is said to be the fiance of one of the three girls, police added.
According to police, the incident occurred on Tuesday night in a tent home set up by a tribal family engaged in crop protection.
The crime occurred at an isolated spot near Khadraya village of the district and came to light yesterday, said Additional SP Kesar Singh.
Four minor girls, three sisters and one cousin, were present in the tent home along with their cousin brother when the incident occurred. The elders of the family had been away on work to Dholpur district.
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After some time, Raju and Kailash, who were known to both Babli and the girls' family, also arrived there.
"The three youths insisted that they would stay for the night, but the cousin brother, Ramjeet, objected and asked them to leave.
"That prompted the accused to fire at him with a gun which was there in the tent," he said.
After killing Ramjeet, the accused allegedly raped the three girls, including the fiancee, before leaving the place.
One of the accused, Kailash, called up the elder brother of the slain Ramjeet and informed him about the incident, the officer said.