Police: Drug probe includes home that exploded

Police say they've executed search warrants in four Michigan counties as part of a marijuana trafficking investigation that included a house that exploded over the weekend.

State police say Monday they're working on the 7-month investigation with the Western Wayne Narcotics team and several federal and local agencies, as well as the state attorney general's office.

Police say 22 search warrants were executed at private businesses, homes and four warehouses. According to police, they seized more than 500 marijuana plants, a large quantity of processed marijuana and several weapons, and took several people into custody.

Authorities in Washtenaw County say three people survived an explosion that destroyed a house Sunday in Ypsilanti Township, east of Ann Arbor.

Investigators tell a water heater is likely to blame for the explosion.