Durham, N.C. — Police investigators said Thursday that they believe an assault on the American Tobacco Trail in Durham this week was sexually motivated and that it's not related to at least 11 other incidents on the trail this year.

The latest attack happened around 6:15 p.m. Wednesday. A woman told police she was walking near the intersection of Apex and Fargo streets when she saw her attacker pass her and then turn around and follow her for about a quarter-mile before knocking her to the ground.

"He jumped on my back, put his arm around my stomach, around my wrist and basically wrestled me to the ground," the woman, Ginny Mueller, said Thursday. "I was screaming as loud as I could. I dropped my phone. I'd been talking to my father."

The two struggled on the ground until a passing bicyclist scared the man away, police said.

"I hit (the attacker) in the face a few times. He responded by hitting me in the face and the back of the head," Mueller said.

Police don't have any suspects and are asking anyone with any information to call Crime Stoppers at 919-683-1200.

The alleged attacker was described only as being a stocky black man between 25 and 35 years old and standing about 5 feet 11 inches. He was wearing all black clothing.

"I keep thinking of what I could have done differently," Mueller said.

One thing, she said, was to have been more aware.

"I was on the phone. I was distracted. I wasn't paying attention," Mueller said. "I think there were some signs that I missed."

So far this year, 12 crimes have been reported on the 7.5-mile section of the trail that runs through Durham – seven assaults, four robberies and one case of indecent exposure.

In 2011, five robberies, two assaults and six cases of indecent exposure were reported on the same portion.

Durham Police Chief Jose Lopez says that the police department has increased patrols in the area and is looking at all possible options – ranging from surveillance cameras to emergency phones on the trail – to help keep the trail-goers safe.

The department has also bought three utility terrain vehicles for use on the trail.

Police urge others to go on the trail in pairs, avoid groups that are loitering in the area and to carry cellphones to report suspicious activity.

Mueller said she'll likely never go for a walk again while on the phone.

"I'd like to carry mace, pepper spray, with me while I'm walking," she said. "That will make me feel a whole lot better."

Mueller added that she does plan to get back on the trail again soon but that it might take her a week or two.

"I'm trying so hard to overcome this and have it make me a stronger person, make me more aware in these situations," she said.