Fire broke out on the Margalla Hills on Wednesday has been spreading and the smoke can be seen from far away.
It is feared that the fire stated due to human error when someone threw a burning butt of cigarette on dried bushes.
Attempts to contain the fire have also begun with apparently no success.
Spread over 12,605 hectares, the Margalla Hills National Park witnesses fire every year during hot and dry summers.
Special measures to prevent the fire this year are in place, as services of 400 locals (who extinguish fire with traditional method of beating fire with bushes) were hired while 200 CDA (Capital Development Authority) own staff is deputed on the hills to control the fire.