One was carrying what looked like a crowbar or metal pipe and as they walked past the shop, they lifted it and smashed the grill and window before running off towards Upper Plain Rd. Nothing was taken from the store.
"They just ran off," Mr Valand said.
Mr Valand, who has owned the shop for about two years, said he was disappointed about the vandalism.
"It's just reckless. It's very scary.
"It's not good at all. It's not good for business."
The window is only temporarily fixed as it could not be replaced until today because of the long weekend break. It is estimated it will cost $500 to $600 to repair the broken window alone.
Meanwhile, Mr Valand said they had an elaborate security system inside and outside the store, with security staff checking the building throughout the night.
"We have had a few things happening lately. We had one guy steal all our newspapers last Saturday and about 18 months ago, someone broke into the garage. We have nine or 10 cameras pointing everywhere and ADT security staff monitors 24/seven."
If anyone has information on the act of vandalism at the Renall St Store & Lotto contact the Masterton Police Station on (06) 370 0300.