"Mr. Haim was declared dead at 2:15 a.m. at Providence Saint Joseph Medical Center [in Burbank, Calif.]," Lt. Cheryl MacWillie of the Los Angeles County coroner's office tells PEOPLE of the Lost Boys star. "He was transported to the hosptial where he was pronounced dead."
L.A. County Coroner Assistant Chief Ed Winter says the official cause of death for the actor, who had a long history of substance-abuse problems, is inconclusive pending an autopsy and toxicology tests. Winter said the LAPD believes Haim may have died from a possible accidental overdose.
An autopsy will likely be performed Thursday, according to MacWillie. Haim was found unresponsive at his mother's Burbank-area apartment.
Police Sgt. Michael Kammert said there was no evidence of foul play.
Police Sgt. William Mann told the Associated Press that the actor suffered with flu-like symptoms before his death and had obtained over-the-counter and prescription medications. "He could have succumbed to whatever [illness] he had, or it could have been drugs. Who knows?" said Mann. "He has had a drug problem in the past."
Haim shot to fame in the '80s after starring in several teen films, including The Lost Boys, Lucas and License to Drive. Most notably, he collaborated numerous times with Corey Feldman, and the pair were dubbed "The Two Coreys." They starred in an A&E reality show with that name from 2007 to 2008.
But Haim struggled with drug addiction for several years. At one point, Feldman told his friend he would no longer speak to him until he got sober.
Additional reporting by BLANE BACHELOR