Investigators have begun a criminal inquiry into the death of a political leader in the German city of Kassel.

Walter Lübcke, the 65-year-old head of the regional council, was found shot in the head with no weapon at the scene, German media reported.

Police said only that the circumstances of the death were unclear and that the crime bureau was leading the inquiry.

“We are deeply shocked by the sudden death of our friend,” said Hesse state premier Volker Bouffier.

According to local website HNA, Lübcke’s body was found on Sunday morning in his garden in the village of Istha. The regional authority said he had died suddenly on Saturday night at his home and left a wife and two grown-up children.

Lübcke was not known as a gun-owner, reports said.

The village had been hosting a beer festival, which ended on Saturday and HNA speculated that he might have met someone at the time of the event.

Lübcke was a leading local member of Mr Bouffier’s ruling centre-right CDU in the central state, running the authority in one of Hesse’s three regional areas for the past decade.

The party praised him as a “bridge-builder who could not have been better”.