The Mean Girls star, 19, was driving a black convertible Mercedes shortly before 5 p.m. "when she collided into the passenger side of a maroon Chevrolet Astro van that was apparently turning in front of her," according to a statement from the Los Angeles County Sheriff's Department. The impact also deployed the driver and passenger air bags in Lohan's car.
According to the sheriff, "Miss Lohan and her female passenger (were) transported by ambulance to a local hospital for treatment of minor injuries." The male driver of the van was taken to the hospital with "moderate injuries."
The chase reportedly began after Lohan had a late lunch with friends at the Ivy Restaurant and then embarked on a shopping expedition that took Lindsay to a clothing store. "Paparazzi were outside the window following her, and she got in her car and zipped off," New Orleans resident Richard Starr, who was in California with his wife, Katherine, tells PEOPLE.
"There was smoke everywhere," said Katherine. "Lindsay jumped out and ran to the antique store."
The van driver, whose name has not been released, will "probably be alright, but he's pretty banged up," said Kirk Martin, manager of the Newsroom Cafe, where the driver works.
A witness inside the ER of Cedars-Sinai Medical Center tells PEOPLE that Lohan and her female friend were taken inside a private room at the facility. "She wasn't crying, but she seemed upset. Mad. She wanted to get out of there," he said.
Said another witness: "She was in and out in 45 minutes. She had a couple of scratches on her legs, but she was totally fine. She was wheeling around having fun. Her friend was pushing her through the hallways."
That witness added: "By the time she left, there were six or eight girlfriends with her ... all 19- or 20-year-olds."
A source close to Lohan tells PEOPLE: "She's shaken up. She's rallying her friends around her for support." Lohan's rep, Leslie Sloane, said: "This is another example of the paparazzi endangering citizens, both Ms. Lohan and the other driver involved in the collision. As the matter is still under investigation, we cannot comment further at this time."
This was Lohan's second such paparazzi-related incident. On May 31 she emerged unscathed from a crash in which a photographer was booked on suspicion of assault with a deadly weapon after hitting her car while allegedly following her, according to Los Angeles police.
Lohan's mother, Dina, said at the time: "I thank God my daughter was able to walk out of the car."
The occurrence also spurred the state of California to enact a law that reins in paparazzi and makes them liable for triple damages to any injured victims. That law takes effect next January.