Police said the deceased, Gunjan Dutt, 18, a resident of Palam Vihar area, was shot late last evening.
She worked as a part time salesgirl in a Patanjali store since last six months.
"She was being stalked by Pawan for last few months. Pawan had been harassing her while on her way to work," ACP-PRO Gurgaon police, Manish Sehgal told PTI.
Dutt was pursuing her graduation from Delhi University School of Open Learning.
"Police on the complaint of her family members, registered a case of murder against Pawan in Palam Vihar Police Station," Sehgal said.
Dutt was later declared dead at a nearby hospital.
"We are examining the CCTV footage and a manhunt is on to nab Pawan who is still on the run," the official said.