All four people on board the small aircraft were killed along with a lorry driver delivering goods to Lidl supermarket car park near Lisbon, Portugal.
The light aircraft is believed to have exploded in mid-air before crashing near the supermarket warehouse shortly after midday. The plane went down in a residential area, about 150m from a school.
The aircraft fell onto a lorry in the car park below, causing it to catch fire and killing the Portuguese driver who was unloading goods at the supermarket’s rear cargo bay. Operational commander Miguel Cruz said the Swiss pilot and three French passengers on the plane all died.
Four people shopping inside the supermarket were treated for shock and smoke inhalation. A nearby house was blackened by smoke, and nine people had to be evacuated from their homes.
The plane had taken off from Tires aerodrome – which is used mainly by private aircraft and situated about 12 miles (20km) west of the Portuguese capital – shortly before the crash.
Officials described the weather at the time of the crash as clear skies with a light wind. The Tires airfield said the plane was a twin-engine Piper PA-31 Navajo aircraft and was Swiss-registered.
A spokesman for the local emergency services said the plane was headed for Marseilles in France. The airfield has now been closed, while authorities begin an investigation into the cause of the crash. Authorities are yet to reveal the names of those who died.