The helicopter crashed near the mountain's Barafu Camp on Wednesday, Tanzania Civil Aviation Authority said in a statement.
Mwananchi newspaper and East Africa TV, citing Kilimanjaro region's head of police, Simon Maigwa, reported that the helicopter was on a medical rescue mission.
Among the dead were a guide, a doctor, the pilot and two foreign tourists, Mwananchi cited Maigwa as saying, without giving the tourists' nationalities.
Mount Kilimanjaro, Africa's highest peak, is nearly 6,000 meters (20,000 ft) above sea level.
The crash happened between 4670 and 4700 metres, Mwananchi reported.
Around 50,000 tourists climb Kilimanjaro annually.