BISBEE, Ariz. — The Cochise County Sheriff’s Office has asked for federal assistance to investigate a fire at the Bisbee City Hall.

The blaze early Wednesday caused substantial damage to City Hall and its cause is unknown.

Sheriff Mark Dannels says the county asked the Bureau of Alcohol, Tobacco, Firearms and Explosives for help due to the size of City Hall and the damage done.

He says ATF has more assets to devote to the probe and expert personnel who deal with fire investigations as part of their assigned duties.

Dannels says the county’s fire investigator is working with a structural engineer and two ATF agents to determine what equipment and resources will best be utilized.

Bisbee Mayor David Smith says city offices will have to be temporarily relocated due to the fire.