Authorities said a customer at the Exxon station at 7898 Ridge Road called shortly after 1:30 a.m. after finding the clerk unconscious with gunshot wounds.
Officers identified the victim as 49-year-old Rajinder Kumar of Glen Burnie.
Friends described him as a nice, gentle father of two children who sent whatever money he could save back to his family in the Punjab state in India.
Investigators said surveillance video showed a man entering the store shortly after 1 a.m., shooting Kumar and stealing an undetermined amount of cash before fleeing.
"It appears the person went in with the intent of robbery, and possibly to kill," said T.J. Smith of Anne Arundel County Police.
The man in the video was described as African-American, unknown age and average build, wearing a dark hooded sweatshirt and tan or light-colored shorts, and armed with a handgun.
(See surveillance footage of the crime below).
Police also said they were looking for some potential witnesses - namely the driver and passengers in a dark-colored Range Rover, possibly with New Jersey license plates, who are believed to have been at the gas station around the time of the shooting.
Police urged anyone with information to call AACPD Homicide Det. Jack Hartzell at 410-222-3460.