(CONCORD, Calif.) — A 60-year-old man was shot and killed by police after allegedly causing his 85- and 90-year-old parents “serious injuries” and refusing to drop a knife while he held it over his mother as he straddled her on the floor. The incident occurred at approximately 11:45 a.m. Sunday in Concord, California when police received a call from the 85- and 90-year-old residents of the home informing them that their son was “acting erratically and was possibly under the influence of drugs and alcohol,” according to a statement from the Concord Police Department. Neighbors also called authorities to report a man was in the front yard of the home wielding a firearm. Police attempted to speak with the man when they arrived on scene but the man ran back into the house instead of engaging with the officers.The attending officers then saw an elderly man visibly suffering from serious injuries walk out of the house. When the police made their way inside the California home they discovered the man straddling his mother while holding a knife.“At that point, two officers used their service weapons. Officers provided medical aid to both elderly victims and the man, but the 60-year-old son was pronounced dead at the scene,” said the Concord Police Department. The 85- and 90-year-old parents of the man were immediately transported to a local hospital where they are being treated for serious injuries. The nature of their injuries is currently unknown.“Anytime force is used, it is tragic,” said the Concord Police. “Our thoughts are with the man’s family during this difficult time.” The City of Concord and the Concord Police Department are now working with investigators from the Contra Costa County District Attorney’s Office to investigate the incident. Copyright © 2019, ABC Audio. All rights reserved.