Police said the incident occurred in Kharal Maldilan village in the disputed Himalayan territory’s Bagh district, some 120 kilometres (75 miles) from the capital Muzaffarabad.
“A six-year-old boy and his nine-year-old sister were killed in the blast while another sister aged 13 and their mother were injured,” Hasan Wazir Afridi, a local police official, told AFP.
“The blast occurred when the young boy discovered an object resembling a ball in the street and took it home to play with his sisters,” he said.
Afridi said it was unclear exactly what the device was or how it came to be in the village, which lies some distance from the de facto border with India.
A senior police official in the region, Riaz Mughal also confirmed the event