A man intruded into a county administration building in northwest German state of Lower Saxony, shooting the county mayor to death, then killed himself on Friday, reported local media.

The shooting happened around 10:00 (0900GMT). Local police in the county of Hamelin-Pyrmont confirmed that the county mayor Ruediger Butte was shot dead in his office.

The shooter, 74 years old, took his own life after killing Butte. Three shots were heard by a witness, according to local Deister-und-Weserzeitung newspaper.

"This terrible act shocked us all. The sympathy of the entire state government is with his wife and family," said Lower Saxony State Prime Minister Stephen Weil in a statement.

According to Weil, Ruediger Butte directed State Criminal Police Office of Lower Saxony for a longtime, and became the mayor of the Hamelin-Pyrmont County since 2005.

"I am deeply saddened by the death of Ruediger Butte. He was a wonderful person...had made great contributions to the internal security and local self-government in Lower Saxony," Weil said.

The administration building was surrounded by strong police forces and a police press conference was scheduled to be held at 16:00 p.m. local time.

The motivation of the shooting remained unclear. There is rumor saying that the shooter is a gun lover. But this information has not been confirmed by the police.