Clint Langford, another neighbor, recalled hearing a low rumbling sound right before the crash.
A two-storey house in the Yorba Linda neighbourhood was struck by part of the plane and burst into flames, causing panic throughout the community.
The Cessna 414A had just departed the Fullerton Municipal Airport when the incident happened under unknown circumstances, Allen Kenitzer of the Federal Aviation Administration told KTLA.
It is still unclear whether or not the pilot is one of the deceased.
Virginia governor denies he is in racist photo, refuses to resign
Demonstrators hold signs and chant outside the Governor's Mansion in Richmond, Va., Feb. 2, 2019. "An apology now isn't enough". The Virginia Legislative Black Caucus wrote in a statement that they were amplifying their call for the governor to resign.
Images from the scene showed flames engulfing the two homes and residents rushing to the scene.
Authorities did not reveal the identifies of the two people who died or of the two that were injured.
Those killed in the home were two males and two females, Orange County officials said at a news conference.
He said he ran to the burning house and saw a woman come out with singed hair. "And then all of a sudden boom".
About 70 firefighters responded to the massive blaze, along with deputies from the Orange County Sheriff's Department. The fire spread to a SUV that was parked in the driveway. They planned to search the burned house in case there were additional victims, Sanchez said.