Four of them have been transferred to nearby district hospital in critical conditions, rescue services said.
The incident with women took place in Chak Mansab Ali of Bahawalnagar city of eastern province of Punjab, where Pakistan Muslim League Nawaz is ruling over.
The hardcore assailants threw petrol on wife of a labour and his three daughters while they were sleeping and fled away from the spot after lighting them.
They include Rani BB, wife of Manzoor Ali, daughters Meraj Fatima, 7, Shaista, 15, and Samina, 16.
As they screamed of the pain they were suffering from fire, neighbours got around managed to extinguish fire and to transfer them to the hospital.
Police, as usual, took a while to register the case against unknown assailants.