The government of the Balearic Islands announced this on Twitter.
The victims included two passengers on the plane, and a couple with their two children and the pilot of the helicopter.
It was also not known what caused the accident, which reportedly happened in the early afternoon near the town of Inca.
“We are concerned and horrified by the accident.
“Our thoughts are with the victims,” Francina Armengol, the president of the Balearic Islands, wrote on Twitter.
Spanish Prime Minister Pedro Sanchez also sent his condolences for the victims’ families.
Police and fire services were called to the scene, as the plane went up in flames, reports said.
Parts of the helicopter were strewn across an old country road, and the plane had crashed onto the grounds of a country estate, Sebastia Oriol, head of security for the municipality of Incam, told local broadcaster IB3.
Authorities have launched an investigation into the cause of the accident.