An investigation is under way after four thieves broke into stores and assaulted a guard before fleeing in west Auckland this morning.

Waitematā West Area Prevention Manager Inspector Jason Edwards said police were investigating an aggravated burglary at a retail complex in Westgate in the early hours of Tuesday morning.

"Around 3.28am, police responded to reports of an incident on Fernhill Drive, where it is understood four offenders have broken into two retail stores within the complex.

"One person in the group has assaulted a security guard at the scene, who has received medical attention for moderate injuries, and is currently recovering in a stable condition."

Police were following positive lines of inquiry and were committed to holding those responsible to account, he said.

Police would be in the area this morning undertaking a scene examination, Edwards said.

Anyone with footage or information that may assist is asked to contact Police via 105 phone service or online at https://www.police.govt.nz/use-105, using Update My Report.

Information can also be provided anonymously via Crime Stoppers on 0800 555 111.

MORE TO COME.