The two women, from a Shell service station on the route between Phuket City and Patong, drove the Mazda pickup and parked soon after 11am at some distance from the entrance to the shopping centre and its banks.
The men, in full-face helmets, pulled a handgun on the women as they alighted and rode off at high speed.
Police from Phuket City Station were questioning the women in detail because of the lax security involved in parking so far from the entrance to the centre while carrying such a large amount of money.
Security cameras provided the only clues they have so far to the robbery.
The Tesco Lotus shopping complex was the scene of a gold shop robbery in April last year in which a bystander, Pichet Chookong, tried to intervene and was shot dead.
The lone killer bandit escaped with 2.4 million baht and there has been no clue to his identity, despite a 200,000 baht reward for information leading to the murderer.
In a reconstruction of the shopping complex, the gold shop has moved inside.