A 60-year-old woman was assaulted Sunday morning at Sonoma Valley Regional Park near Glen Ellen after her dog got into a fight with another man's dog and the man became enraged, authorities said.

During the attack, the suspect wrapped a dog leash around the victim's neck, ripped off her glasses and threw her cellphone into a lake after she threatened to take a photo of him, Sonoma County Sheriff's Sgt. Dave Thompson said.

The man, who was described as being in his 50s and about 6-feet tall, kicked the woman's dog several times before he took off running toward Arnold Drive. He was being sought Sunday afternoon.

The 8:50 a.m. altercation occurred on Sutton Lake Trail, about a half-mile in from the Highway 12 entrance, which is where the victim accessed the 162-acre park.

Thompson said he did not know the breed of the woman's dog, which he described as medium-sized and black-and- white in color. The man's dog was described as a reddish-brown and white Australian Shepherd.

Thompson said both dogs were running off-leash in violation of park rules. Dogs are allowed to roam free at the park only in a fenced-in area near the Highway 12 entrance.

Thompson said after the dogs began fighting, the man began yelling at the woman and then came at her from the front with his dog's leash, which he wrapped around her head and began to pull tight.

The woman fought that off. The man continued to scream at her and then yanked her iPhone 5 from out of her hands when she went to take a photo of him.

Thompson said crime victims increasingly resort to using their cell phones to try and document what's happening.

"Obviously, if you can do it from further away or a place of safety, with a witness, it would be better. But a lot of times you don't have the opportunity," he said.

Thompson described the man's behavior as "way over the top and criminal." He said the man's actions amounted to criminal assault, robbery — for tossing the woman's cell phone into the lake — and animal cruelty.

The suspect took off running toward Arnold Drive after he kicked the woman's dog several times. Sheriff's deputies and Sonoma Developmental Center police searched for the man with assistance overheard from the Sonoma County sheriff's helicopter Henry 1.

The assault was reported after the victim flagged down another hiker, who went for help. Thompson said the woman suffered minor injuries to one of her hands as a result of her cell phone being taken away.

"She was very shaken and upset by the ordeal, obviously," he said.

The suspect was described as a slightly-built white male in his 50s, about 6-feet tall, with gray hair and a brown and gray beard. He wore a red baseball cap, blue vest and shorts with a fanny pack.

Anyone with information is asked to contact the Sonoma County Sheriff's Office at 565-2121.

You can reach Staff Writer Derek Moore at 521-5336 or derek.moore@pressdemocrat.com. On Twitter @deadlinderek.