The renewed violence on Thursday comes before weekend talks in New Delhi between the foreign ministers of the two nations in a new push to end their decades-old Kashmir dispute.
Indian police said three of the fighters were shot in the Trikunda sector of southern Rajouri district after crossing into Indian-administered Kashmir, and a fourth in northern Kupwara district.
"They entered our side after crossing the Line of Control," a police spokesman said.
Meanwhile, suspected fighters on Wednesday night shot dead Nazir Malik, a senior functionary of the state's ruling Peoples Democratic Party in central Budgam district, police said.
Also on Wednesday night, fighters shot dead a former colleague now working for Indian troops in the southern town of Anantnag, police said.
In another incident, six paramilitary soldiers and three civilians were injured on Wednesday night when suspected Islamic fighters hurled a grenade at a patrol guarding Srinagar's Mughal-built Nishat garden on the east of Srinagar's picturesque Dal Lake.
The garden was built by Emperor Jehangir in the 16th century and is one of the main tourist attractions in Srinagar, the state's summer capital.
India and Pakistan both claim the scenic Himalayan state in full and three wars have been fought over it. According to government figures, around 40,000 have died in the 15-year-old insurgency against Indian-rule while separatists place the figure at about 90,000.