Divers spent most of Tuesday combing through the waters of a Cape Breton bay after a car drove off the Englishtown Ferry and plunged into the bay Monday night.

Emergency crews rushed to the shores of St. Ann’s Bay just before 9 p.m.

RCMP Sgt. Alain LeBlanc says the car drove from a dock at St. Ann’s Bay onto the cable ferry and picked up speed before plunging off the end of an upright ramp at around 8:45 p.m.

“The person working on deck tried to gain the attention of the driver by tapping on the window to get his attention, but the person continued on through the gate and over the side,” says Staff Sgt. Craig Yorke of the Baddeck RCMP.

The car landed in the water, about 20 to 30 metres from shore, and was last seen about 200 metres from where it entered the bay.

The make of the car or the number of occupants inside remain unknown.

“There’s very little information,” LeBlanc told CTVNews.ca on Tuesday. “It happened very fast and the ferry crew didn’t have a lot of time to look at car.”

The search for the vehicle began Monday night with divers from the local fire department and continued into Tuesday afternoon.

A volunteer who was among the first to arrive on the scene Monday night says weather conditions hampered search efforts.

“The fog was thick, couldn’t see too much,” says searcher Scott MacRae. “I was out until 2:30 this morning, then back at six.”

LeBlanc said RCMP Underwater Recovery Team arrived at the scene around 9:30 a.m. Tuesday but had yet to locate the vehicle.

He added that the current in St. Ann’s Bay is quite strong.

“The undertow there is ridiculous,” says local fisherman Keith Burroughs. “It’d pull you away in a second, as soon as you hit the water.”

Rescue crews spotted what looked like an oil slick in the water at approximately 10 a.m., where they felt the vehicle could have been submerged.

However, three dive teams later, there is still no sign of the vehicle.

There is also no word at this time on what caused the vehicle to plunge off the ramp.

“Anything could have happened,” says Yorke. “We don’t know what was going on in the mind of the individual at the time, or if it was a medical problem or what.”

The Department of Transportation and Infrastructure Renewal is assisting RCMP as they investigate.

"My first thoughts are for all involved at this difficult time," said Transportation and Infrastructure Renewal Minister Maurice Smith.

"Along with the RCMP, we are following through with our own standard protocols that includes an internal investigation on what happened."

Department officials are inspecting the ferry and interviewing two crew members who were working at the time of the incident.

RCMP say they will likely wrap up the search Tuesday night, before deciding what to do next.

The Englishtown Ferry, which went into service in 2008, will be out of service until further notice.

With files from CTV Atlantic's Ryan MacDonald and CTVNews.ca