Two security guards and a store manager at a Sears store were stabbed by a shoplifter when they stopped the man as he tried to carry a box of electric razors out of the store, police said. The thief, who dropped the box as he scuffled with the three men, escaped down an alley behind the North Hollywood store. In stable condition were automotive department manager Garth Marcus, 32, and security guards Harry Roundtree, 36, and Marvin Ramsey, 38. One of the three was stabbed as he stopped the thief on his way out the door. Police said the thief broke free, ran about 50 feet, and stabbed the second man who grabbed him, then eluded a third man after also stabbing him. Police said the shoplifting incident was recorded by security cameras.