Two men allegedly broke into Utopia Tanning in High Street, Selsey, at about 10.30pm and tried to make off with 'several' items of clothing, the business has said.
One of the men was reported to have been wielding a machete and attempted to use it after a member of public 'heroically' stepped in to help.
No injuries have been reported.
The Selsey community has been thanked by the shop which said its neighbours had been 'amazing'.
Sussex Police has been approached for more information.
In a statement on Facebook, Utopia Tanning said: "Last night at around 22:30 two young men broke into our shop on the high street and attempted to steal several items of clothing.
"One of them was carrying a machete and aggressively tried to use it on a neighbour who heroically stepped in to help. Unfortunately they managed to get away before the police got there. Thankfully nobody was hurt.
"The idiots did manage to drop one of their balaclavas which the police now have. If anyone has any further information, we’d really appreciate it if you came forward. Several people already have, but the more evidence we gather the better.
"Lastly thank you to all of our Selsey neighbours who have been amazing! Especially the local café and barnyard butchers.
"Alan you really are a hero! Thank you.
"We aim to get back up and running as soon as possible! We’ll be in touch when we know more."