CASTRO VALLEY (CBS SF) – A submerged car was located under the rain-swollen waters of Alameda Creek Monday, but authorities could not confirm it was the vehicle driven by a missing Tracy 18-year-old.

The Tracy teen has been missing since a witness reported her car had careened into the waters after a collision and disappeared under the rushing water during stormy weather on Saturday.

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Her family was at the scene Monday, walking along a section of Niles Canyon Road between Fremont and Sunol, hoping to catch a glimpse of her missing silver Honda. Nearby, frustrated search teams were being forced to stand on the shoreline because the creek was too dangerous to enter.

Alameda County Sheriff’s spokesman Sgt. Ray Kelly said the currents were just too swift for divers to safely maneuver.

“The water levels are still very high,” he told reporters. “We are looking at class 2 or 3 rapids … In the section of the creek where we believe the vehicle went into the water – that section is very challenging … We can’t put anyone into the water today.”

Authorities were working with state and local water officials to take measures to reduce the water levels in the creek. Run-off from dams at both the Del Valle and Calaveras reservoirs would be turned off.

With the steady rain ending, water officials also said they expected the level of the creek to begin dropping by itself at midnight.

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Kelly said drones would be flown over the creek on Monday allowing authorities to begin the 3-D mapping process in the hopes of locating the car.

Authorities believe the teen was not able to get out of the vehicle before it sunk into the churning waters Saturday morning.

“We are really hoping she is in the car,” Kelly said. “If she was wearing her seat belt it likely kept her in the vehicle.”

CHP spokesman Officer Derek Reed said that at about 10:45 a.m. Saturday, the teen’s Honda was traveling west on the road when it crossed into the eastbound lane and collided with a 2016 white Honda Accord.

After striking the white car, the teen’s car careened into the creek and was completely submerged by the time officers.

A witness who saw the car floating down the creek after the collision was brought back to the scene Monday and attempted to help authorities pinpoint where the Honda may have sunk.

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Officials said access to Niles Canyon would be shut off intermittently to help authorities in their search.