LOS ANGELES—Two people and a dog were rescued from a rain-swollen Southern California river Monday as a vigorous late-season storm moved slowly through the state, bringing heavy showers and snow. A helicopter rescue crew pulled the dog’s owner, a woman, from the rushing Los Angeles River, in the San Fernando Valley, around 2:40 p.m. But the dog slipped away and continued for more than an hour down the river, which runs through an inaccessible channel with high concrete walls for several miles. At one point a good Samaritan jumped into the raging river and grabbed the dog, but the animal slipped from his grip too and the man had to be rescued himself. The medium-to-large black and brown dog eventually reached shallower water, where it was able to walk, and an LA Fire Department crew on the ground pulled it to safety around 4 p.m. to the cheers of bystanders. …