An Ashland man whose alleged carjacking attempt was thwarted by the intended victim and a Good Samaritan has been held without bail. Prosecutors said Louis Torres, 23, approached a man outside a supermarket Sunday, told him he had a gun, and demanded his car keys. The MetroWest Daily News reported that Torres punched the man and hit him with a backpack, before the victim fought back and subdued Torres with the help of a passerby. The victim held Torres until police arrived. No gun was found. Torres faces several charges, including armed carjacking.