The traffic accident occurred on Friday along the Moscow-Kazan highway near the town of Dzerzhinsk.
"The driver of a Hyundai broke traffic rules and crashed into a Mercedes. As a result of the crash the Hyundai driver and his four passengers were killed instantly, the driver of the other vehicle and his two passengers were seriously injured," the police source said.
The injured are currently in intensive care at a local hospital.
Police are investigating the fatal accident.