The other man, who had a knife, was wearing a dark grey or black hooded top and had a dark scarf over his face. He had on a white T-shirt, blue jeans and white trainers.
Detective Sergeant Steven Adams, from Strathclyde Police, said: "I'd like to reassure the local community we are doing everything in our power to catch the men responsible. Officers are carrying out door-to-door inquiries and examining CCTV footage.
"This has been a very frightening experience for the members of staff within the shop.
"I would appeal to people to get in touch with us. Any information could prove vital in helping officers track these men down."
Anyone with information is asked to contact Paisley police office on 0141 532 5900 or Crimestoppers in confidence on 0800 555 111.