A third youth has been taken into custody over a wounding incident in Launceston.

A man was seriously injured during the incident at a shopping complex in Racecourse Crescent on Wednesday evening.

A 15-year-old and 16-year-old were taken into custody in the early hours of Thursday morning, and a 16-year-old was taken into custody just before noon.

Police are continuing to follow a specific line of inquiry in relation to a fourth youth.

The victim remains at the Launceston General Hospital in a serious, but stable condition.

Anyone with information about the incident should contact police on 131 444 or Crime Stoppers anonymously via crimestopperstas.com.au