Russell Ord was videotaping surfers Saturday when he saw two large waves hit the group at Mavericks, a famous surf spot north of Half Moon Bay.
He says the first wave "cleaned up" about five riders and the second wall of water hit around 20 seconds later.
Ord told CBS's "The Early Show" Tuesday that the injured surfer, 30-year-old Jacob Trette, was "full of water" but had a pulse. A spokeswoman at Stanford Medical Center says Trette is still in critical condition.
The San Francisco Chronicle reports that Trette is an accomplished surfer from San Clemente but had attempted the waves at Mavericks just once before.
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