Lindsay Lohan was arrested Saturday after a late night turned into the early morning and her convertible car struck a curb. Police say they found what appears to be cocaine in the car.

Los Angeles police announced at a news conference Saturday afternoon that officers found a "usable amount" of a drug in the actress' 2005 Mercedes SL-65, which crashed on Sunset Boulevard around 5:30 a.m.

Lohan, 20, and two other people were in the car, and Sgt. Mike Foxen said it appeared Lohan was speeding.

Officers at the scene found a "usable amount" of a drug tentatively identified as cocaine, McCann said. He declined to say where the drug was found, but added that Lohan was not carrying it.

The celebrity paparazzi company X17 reports on its website that its photographers have followed Lohan since she completed a rehab program a few months ago.

"X17 photogs witness Lindsay out on almost a nightly basis and she's not a 2 a.m. kinda girl," the website says.  "She regularly gets home at 5 and 6 in the morning and my personal opinion is that you usually don't make it that far without some gas in the tank, if you know what I mean ..."

After the accident, Lohan was driven in another car to a hospital for treatment of minor injuries.  Police arrested Lohan at the hospital for investigation of misdemeanor driving under the influence of alcohol or drugs.

She was released from custody because she was admitted to the hospital, police said.

In 2005, Lohan's vehicle struck a minivan carrying paparazzi who were on her tail after a meal at a Los Angeles restaurant. 

After that incident, California Gov. Arnold Schwarzenegger signed a law that set financial penalties for paparazzi who commit assaults while trying to snap celebrity shots.

X17online.com has an hour-by-hour account of Lohan's party-until-dawn escapades, starting at midnight when she apparently left her condo and went to a nightclub with her bodyguard Jaz.

Photographers followed her as she moved on to a private house party in the Hollywood Hills, and then to the Skybar lounge. She made her way back to her condo in the wee small hours, then departed again at 5:15  a.m. and lost control of her car on Sunset Blvd., a few blocks away from home.

X17 concludes its reporting on Saturday's arrest by saying: "But we're glad Lindsay wasn't seriously injured and we wish her the best."

With files from Associated Press