Officers, tow truck driver released from hospital after Fentanyl exposure scare on Golden Gate Bridge.

SAN FRANCISCO (KGO) -- Four CHP Officers, a Golden Gate Bridge Patrol Officer, and a tow truck driver have all been released after they were possibly exposed to the Opioid drug, Fentanyl. The initial driver who was found unconscious in a vehicle on the Golden Gate Bridge is still hospitalized.

Seven people were initally hospitalized after possible fentanyl exposure during a car crash investigation near the Golden Gate Bridge on Sunday morning, CHP officials said.

At around 11:45 a.m. Sunday morning, officers responded to a 911 call of a vehicle swerving in and out of its lane, close to colliding with the median northbound of the Golden Gate Bridge toll plaza, a CHP official said.

CHP and Golden Gate Bridge patrol officers responded to the scene to find the vehicle had crashed on the Alexander Avenue off-ramp in Marin County.

The first CHP officer to enter the crashed vehicle started feeling "extremely ill and displayed symptoms of a possible fentanyl exposure," Andrew Barclay with Marin CHP said. "Very soon after that he went down and essentially became unresponsive."

Additionally, the second CHP officer, patrol officers and tow truck driver began displaying symptoms of chemical exposure.

Officials located a white powdery substance in the vehicle that they believe to be fentanyl.

Dr. Anna Lembke of Stanford University says that Fentanyl is 50 to 100 times stronger than morphine and if this was Fentanyl, it could have easily been deadly.

"Sadly, there are more opioid overdose deaths caused by Fentanyl today than by any other opioid it has made its way to the illicit market," Dr. Lembke said. "People are taking it without realize they're taking it. They're buying what they think are pills of pharmaceutical grade opioids or using heroin at a stable dose and in fact that supply has been contaminated with Fentanyl."

CHP officers believe a powder form of Fentanyl was in the vehicle and that those affected breathed it in.

Due to the extreme danger of fentanyl exposure, the Alexander Avenue offramp from northbound U.S. Highway 101 (as well as the on ramp there) were closed and the area was deemed both a crime scene and hazmat scene.

Resources from the CHP, Marin County Fire, Marin County Sheriff's Office and the Marin HAZMAT team all responded to the scene to clean up the vehicle and making it safe for removal. The on and off ramps at Alexander Avenue are now open.

Stay with ABC7 News for more information on this developing story.