Ontario police officers found the man suffering from a shooting wound in a retail business parking lot.
The 49-year-old Ontario man, whose name has not been released, was transported to an area hospital for treatment of the gunshot wounds. He was later pronounced dead at the hospital, according to a police news release.
Patricia Gonzalez DeReynaga, 36, of Ontario was arrested a couple of hours later in the 300 block of East Philadelphia Street, according to the news release.
DeReynaga was booked into West Valley Detention Center in Rancho Cucamonga on a murder charge.
A police official said that the man and DeReynaga were in a relationship.
Anyone with information about this incident can call the Police Department at 909-986-6711 or 909-395-2777.