Watch: Tractor-trailer plunges off bridge into river; driver unharmed, police say

WESTON, Mass. (WLS) -- A tractor-trailer plunged off a bridge outside Boston on Saturday.

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A video shows the truck, coming from the right-hand side, crash off a bridge and fall into the Charles River, which is located in Weston.

The driver, incredibly, was not hurt. He was able to climb out and stand on top of the vehicle until rescuers came. What caused the driver to lose control is not clear.

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Officials did not provide further information about the incident.