My wife and I were returning to work from lunch in Laguna Niguel, CA, and we observed a very fast moving object leaving a very distinct smoke trail traveling accross our line of sight at about 60 degrees above the horizon. The speed the object moved caught our attention and we watched it and could see it reflect light at one point, but we could not see wings or any lights or markings. The reflection suggested the object was bullet shaped -we assumed it was a military jet or something similar because of the very fast speed it was moving - much faster than a passenger jet, which are extremely common in the skies above where we work. Just after the point it passed closest to us and began flying away from our point of reference, the object disappeared and the trail came to an abrupt end. Although the object was no longer visible and the smoke trail came to an abrupt halt, the remaining trail was still clearly visible and intact along the path the object had traveled prior to disappearing. I took 2 pictures with my cell phone which focus on the point the smoke trail ended. To clarify, there was not a "trailing off" of the smoke - it just stopped abruptly as if it had been severed, for lack of a better description. The object did not turn or land and the smoke trail remained in a perfectly straight line, from our vantage point. I would estimate the object to have been flying at about 20,000 feet. I am not able to load the pictures onto this computer, but the pictures are available and I can supply them upon request.