They did, at the checkpoint, exactly what they always do -- shoot if you don't stop. Even I know that.
In her article, Sgrena wrote that her captors warned her as she was about to be released not to signal her presence to anyone, because "the Americans might intervene."
This is odd, to me -- 'not to signal to anyone' would ensure that the Americans shot at them if they drove at a high rate of speed, wouldn't it?