The offences took take at Sainsbury’s on Shenley Road, Woodhall Farm.
Police have released CCTV images of men that they believe may have information useful to the investigation.
PCSO Simon Jackman said: “We appreciate that they are wearing face masks however, perhaps you recognise their clothing or their stance? Please get in touch if you can help.”
Email [email protected], report information online, use online web chat or call the non-emergency number 101.