Iraqi officials say gunmen have shot dead eight members of a family inside their house north of Baghdad.

Two police officers say the assailants broke into the home of a well-known lawyer in the city of Beiji, 250 kilometers (155 miles) north of the capital. They killed him, his wife, his five sons and a relative. The police did not know the motive.

A health official in the city's hospital confirmed the casualty figures. All officials spoke anonymously as they were not authorized to release information.

The attack followed a threat last month by al-Qaida's Iraq branch to assassinate judges and investigators.

The oil center of Beiji is a former stronghold of Sunni insurgents. Violence has declined in Iraq since its height between 2005 and 2008 but attacks continue.