An off-duty Los Angeles Police Department officer shopping with his family at a Costco in Corona, California Friday was allegedly assaulted by a man whose family says had a mental disability, and the officer responded, police said, by shooting and killing the man.

Kenneth French, 32, of Riverside, was identified Saturday as the person killed in the incident, which took place Friday around 7:46 p.m. in the 400 block of North McKinley Street. Two of his family members were also struck by bullets and were in critical condition, the Corona Police Department said in a statement released Saturday.

The only weapon involved in the incident belonged to the off-duty police officer, who has yet to be identified, police said.

French’s cousin, Rick Shureih told NBCLA Sunday that French had a mental disability and described him as a "gentle giant." Shureih said that French was non-verbal, non-violent and had no issues in the past.

Shureih also identified the two other people injured in the shooting as French’s parents, Russell and Paola French, who monitored and took care of their son. They remained in the hospital Sunday, with Russell doing much better, Shureih said. Authorities have not released their names.

Shureih said that Russell and Paola French were both shot at least once, with Russell doing much better as of Sunday.

Although fears of an active shooter sent the store into a panic, authorities said the investigation concluded that this was an "isolated occurrence" and that it "was not an uncontained active shooter incident."

Unprovoked, a man unknown to the off-duty officer and his family assaulted the officer while he was holding a small child, the Corona Police Department said in Saturday's statement. The child was not injured in the incident, and the officer was taken to a local hospital and subsequently released, police said.

Multiple law enforcement agencies were investigation the shooting, including the LAPD.

If you witnessed this incident and have not provided your statement to the police, please contact Lieutenant Newman at 951-817-5788 or email Robert.Newman@CoronaCA.gov.