(CBS/AP) -- Sheriff's SWAT teams were proceeding with extreme caution as they searched rural Northern California for Shane Franklyn Miller, an ex-convict suspected of killing his wife and two young daughters Tuesday.
Given Shane Miller's knowledge of the area in Humboldt County and ability to fortify himself, deputies were very vulnerable, Shasta County Sheriff's Lt. Dave Kent said. Miller is believed to be on foot, heavily armed and near a cabin in the area where several weapons may be kept.
"Who knows whether or not he would retaliate against officers," Kent said. "With the information we're receiving, it ups the ante. It's almost like warfare."
Miller, 45, is believed to have killed his wife, 34-year-old Sandy Miller, and their two daughters, 8-year-old Shelby and 4-year-old Shasta. The three were found shot to death at their home in rural Northern California at around 8 p.m. on Tuesday.
Wednesday, authorities found an abandoned truck they believe belongs to Miller.
The search is focused around the community of Petrolia, which is close to where Miller's truck was found. Schools in the area were closed, and the roughly 300 residents were being advised to stay in place and keep their doors locked. They were also told by authorities to leave a contact number tacked to their front doors if they do have to leave for an emergency.
Petrolia is about 260 miles north of San Francisco, in a remote, undeveloped area of redwoods and mountains known as the "Lost Coast."
In 2002, Miller was charged in San Francisco with making and selling marijuana for distribution, being a felon in possession of a firearm, possessing a machine gun and money laundering, according to court records. He pleaded guilty to being a felon in possession of a gun and was sentenced to three years and 10 months in prison.
He was released in May 2007, according to the federal Bureau of Prisons.