A Los Angeles grandmother was stabbed to death along with her dog while out on a walk in broad daylight Thursday afternoon, and the alleged perpetrator was reportedly stopped from hurting others when another would-be victim chucked a rock at the suspect's face and knocked him out.

What are the details?

Jeanne Edgar, 66, was walking her dog near San Dimas Park at around 1:30 p.m., when a man who appeared to be in his 20s stabbed her and her pet to death.

"The suspect grabbed the female victim's dog by the leash and yanked it free of her grasp," authorities said, according to Fox News. "The suspect then stabbed the dog and then the female victim."

Reporter Bill Melugin of KTTV-TV tweeted, "This was one of the most horrific crime scenes we have ever seen at @FOXLA. Some lunatic w/ a knife savagely stabs to death a 66 year old woman & her dog in a random broad daylight attack in San Dimas. A bystander with a rock knocked him out before he could attack anyone else."

KCAL-TV reported that deputies learned that the suspect, Ricardo Saldivar, allegedly tried to attack a man in his 30s just prior to murdering Ms. Edgar — but the would-be victim returned to confront Saldivar and knocked the accused man out.

"From what I gathered from my son-in-law, Joe, [Saldivar] actually came after him, first with the knife," Tony Page told the outlet Thursday. "My son-in-law was able to get to his vehicle safely."

"At that point, the guy started attacking the lady that was walking her dog, started killing the dog with the knife then turned the knife on her and started killing her," Page continued. "[Joe], at that point, got out of his vehicle, found a rock, threw the rock, hit the suspect in the face, knocked him out and right shortly after that the authorities arrived."

Deputies recovered a knife at the scene and took Saldivar into custody. He was treated at a local hospital before being booked on suspicion of murder and attempted murder. He remains jailed on $2 million bail.