The incident occurred near the border dividing Jammu and Kashmir from Pakistan's Punjab province, Pakistani officials said.
"At least four people including a woman were killed and six others were injured when Indian troops opened fire across the border in Nakyal sector," local official Zeeshan Nisar told AFP.
Nakyal lies on the Line of Control.
He said the cross-border firing started at 8:00 am and continued through Monday with no break.
Adnan Khursheed, another local official, confirmed the firing and casualties.