Actress Anne Heche was under the influence of cocaine and possibly fentanyl instead of alcohol at the time of the accident.

According to aceshowbiz.com, Los Angeles Police Department sources informed TMZ that the 53-year-old's blood test results came up positive for both substances.

However, the insiders noted that fentanyl may have been administered to her at the hospital to lessen her pain.

Thus, more testing is needed to determine whether she had fentanyl before she slammed her blue Mini Cooper into a Mar Vista home last Friday. The residence caught fire, resulting in the Emmy-winning actress suffering burns from the incident. She was then intubated while hospitalised.

"The vehicle was heading east on Preston Way at a high rate of speed, entered the T intersection at Preston Way and Walgrove Ave, ran off the road and collided with the residence in the 1700 block of Walgrove," a Los Angeles Police Department spokesperson said in a statement.

"The vehicle became engulfed in flames and the driver was transported to a local hospital by LAFD."

Of Heche's condition, a spokesperson said: "Over the weekend a representative stated that Anne was in stable condition but that information was inaccurate. She has always remained in critical condition, slipping into a coma following the accident."

"At this time she is in extreme critical condition. She has a significant pulmonary injury requiring mechanical ventilation and burns that require surgical intervention," the spokesperson added. "She is currently being treated at the Grossman Burn Center."