Police say the clerk, identified only as Jonathan, saved four people by herding them into a back room after a pair of armed men stormed inside.
The incident happened just before 7:30 a.m. Monday at University and West Tremont avenues in the Morris Heights section.
The customers say Jonathan barricaded the door with his own body as one of the gunmen shot out the plexiglas window. In total, police say four shots were fired inside the store.
Everyone came through the ordeal unharmed.
Police are still looking for the suspects, and they hope surveillance video will help lead to arrests.
Anyone with information in regards to the whereabouts of this missing person is asked to call Crime Stoppers at 1-800-577-TIPS (8477).