The girl was raped in Nepura village in Nawada Saturday.
"Karku alias Mukhia of the same village was arrested," Saharyar Akhtar, a district police official, told IANS yesterday. The medical report has confirmed the rape.
The girl was first admitted at a Nawada hospital and later shifted to Patna Medical College and Hospital here after her condition deteriorated.
In the last 48 hours, at least half a dozen rape cases were reported from across Bihar, police said.