She jumps, shrieking as well as he goes over. After a moment, though, she regains control, casting around for something to reach him with. And... nothing but the wood of the bridge itself appears to her.

She decides to go a different route. With a murmured swear, she crouches by the bridge's edge and takes off her shirt, holding it by the edge of the sleeve and tossing it into the water. "Hold on!" she yells as he thrashes in the water.