The teller was unharmed and had been referred to Victim Support, he said.
"This sort of threatening behaviour is thankfully rare in our area," said Mr Bysouth.
"We are following positive leads and hope that with the public's assistance we can resolve this matter quickly."
The teller was fortunately unharmed, said Jeremy Clarke, public affairs manager of Chevron New Zealand which markets its products under the Caltex brand. "From all accounts, the teller is okay, obviously it's an unnerving situation.
"My understanding is a person attempted to rob the service station and ended up leaving before he took anything."
Wairarapa police have released CCTV images from the store in the hope of identifying the man who is described as about 165cm tall. Along with the mask, he was also wearing blue three-quarter length hunting type fleece with a v-neck, black trousers and black shoes with white soles.
"The full-head mask was described as being similar to a witch's mask with long grey hair."
Mr Bysouth encouraged people to look at the CCTV images carefully and talk to their friends. "If you recognise the man in the photo or have seen any of these items he is wearing, make contact."
Contact Wairarapa police on 06 370 0300 or alternatively, information can also be provided anonymously to Crimestoppers on 0800 555 111.
