The man shot and killed by Sunnyvale Department of Safety on Thursday was brandishing a BB gun, authorities said at a news conference Friday.

Police were serving a search warrant on Glen Griggs' Sunnyvale home Thursday morning. They say he is suspected of killing Molly Anne Franquemont, 39, who used to live with Griggs but was last seen in March 2013.

Four Sunnyvale DPS officers involved are now on routine paid administrative leave. Authorities said Friday Griggs was asked several times to drop his weapon before the officers opened fire "out of fear for their safety."

Capt. Jeffrey Plecque has not yet said why police believe Griggs killed Franquemont, or how she died. Her body has never been found.

The last time a Sunnyvale officer shot and killed a suspect was in August 2013.

The Sunnyvale DPS Investigation Unit is continuing its criminal investigation into the homicide case of the Franquemont case as well as Thursday's shooting.

NBC Bay Area's Bob Redell, Derek Shore, Alan Waples and Shelby Hansen contributed to this report.