The mishap took place when a jeep packed with passengers crashed into an unidentified heavy vehicle on the Mumbai-Pune Expressway while overtaking at Kalamboli at about 3.20 AM, they said.
The jeep was carrying 10 persons, including the driver Dhanaji Lodle. Seven passengers were killed on the spot while three others - two jeep occupants and the driver - were injured. They were admitted to a nearby hospital, police said.
The jeep was heading towards Thane from Pune.
Among the passengers were a group of six people, who were returning home in Thane after attending a wedding reception in Satara, about 250km from Mumbai, police said.
Lodle has been booked for rash driving.