According to the New York Daily News, Witherspoon (Legally Blonde), 29, was chased by photographers when she exited her gym.
"Her trainer came out and had to help her get past them so she could get into her car," a source told the Daily News.
"Then they boxed her in on all four sides. When she finally pulled out, they jumped in their cars and took off after her. They almost ran her off the road. They chased her all the way home to where she lives in a gated community. The security guards jumped out and had to assist her to get away from them."
When Witherspoon arrived home, she called the police, who came immediately. The photographers were gone before squad cars arrived, but they will continue to look for suspects, and take this sort of thing very seriously.
Witherspoon lives in Los Angeles with her husband Ryan Phillipe and their children Ava Elizabeth, 5, and Deacon, 18 months.