SOUTHERN Downs residents been left devastated after they discovered six of their alpacas had been shot in the head on their Glen Aplin property.

Five of the alpacas were killed, but one of the animals was so badly injured it had to be put down.

Stanthorpe Police Senior Constable Jim Ellis said a small calibre firearm was used to carry out the shootings in a small paddock on the property.

"It's a very senseless and cruel act, they're animals which are people's pets and don't present a threat," Sen-Constable Ellis said.

The animals are believed to have been shot between Wednesday and Friday this week, but the owners made the shocking discovery on Saturday morning.

No other offences were committed in conjunction with the killings.

The shootings come just eight months after seven alpacas were shot dead on a Lyra property.

Sen-Constable Ellis urged anyone with information about either incident to contact Crime Stoppers on 1300 333 000.

"Whilst we can't link the two, they are very similar in nature," Sen-Constable Ellis said.