Kabul, Afghanistan (CNN) -- An influential Muslim cleric, his brother and a driver were killed in an ambush in eastern Afghanistan, authorities said Monday.

Gul Rahman and the two men were killed Sunday evening, said Edress Gharwal, governor spokesman for Kunar province.

They were killed by those who are against peace and stability, Gharwal said. He did not provide details.

Rahman is an ex-Islamic Party member and influential in the province. He joined the government and was instrumental in pushing for peace and stability in the country through a reconciliation program.

The Interior Ministry is investigating.