NAPA (CBS SF) — Authorities arrested four people Thursday at a Napa home, where detectives found marijuana plants and evidence of the manufacture of concentrated cannabis.

Detectives with the Napa Special Investigations Bureau first arrived at the residence, located in the 3700 block of Oxford Street, to conduct a probation search at the home of Sadie Francis, 49, authorities said.

READ MORE: UPDATE: 2 Pedestrians Killed, 1 Hurt In Horrific San Jose Collision

There, detectives seized marijuana that was growing in the home’s backyard. Detectives also found evidence of the production of butane honey oil, a form of concentrated cannabis, in the garage, according to the NSIB.

Detectives then obtained evidence that linked the four people living in the home to the butane honey oil manufacture and marijuana cultivation, authorities said.

READ MORE: Search Underway For Aggressive Mountain Lion In Belmont Neighborhood

Authorities arrested Sadie, her two sons Raymond Francis, 29, and Kevin Francis, 27, as well as her boyfriend Thomas Sour, 53, according to the NSIB.

All were arrested on suspicion of manufacturing a controlled substance and cultivating marijuana. Sadie was also arrested on suspicion of violating the terms and conditions of her probation, authorities said.

Manufacturing BHO in residential areas is concerning because of the fire hazards associated with it and its close proximity to residents and children, the NSIB said.

MORE NEWS: Three Of Tonga’s Smaller Islands Badly Damaged By Tsunami; Concerns Mount Within Bay Area Tongan Community

© Copyright 2015 by CBS San Francisco and Bay City News Service. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.