Police found "Max" dead near the South Hayward BART station. They also found a gun under a car.
They took one man into custody in the parking lot and they held BART service for nearly a half an hour as they took another man into custody on a train.
The family says "Max" was not aggressive and had run out the front door Thursday night when he was about to be walked.
"It couldn't have possibly done anything to them, but I guess some people are just that heartless," said dog owner Maria Juarez.
Police are questioning the two men they took into custody, but they have not yet been named suspects.