The accident took place in Ambala district, about 45 km south of Chandigarh, the capital city of Haryana.
“In the wee hours today seven people, including two minors, were killed and four others injured after their cars were hit by an unidentified vehicle on Ambala-Chandigarh highway here,” a police official in Ambala said.
“We are being told the cars had stopped on road and the vehicle hit them from behind,” the police added.
The injured were immediately removed to the nearest hospital and from there they have been referred to PGI hospital, Chandigarh.
According to police, the victims hailing from Chandigarh were heading to Vrindavan in neighbouring Uttar Pradesh.
Officials say there was dense fog in the area and visibility on road was poor.
Reports said after hitting the two cars, the vehicle fled from spot.
Police have registered a case and ordered an investigation into the accident.