A hooded man armed with a knife made off with cash after a shop hold-up in Birkirkara on Wednesday, the second such case in three days in that locality.
The police said the latest case took place at 12.30pm in a shop on St Helen Street.
No one was injured.
Magistrate Donatella Frendo Dimech is leading an inquiry.
In the earlier case, a hooded man armed with a knife made off with cash during a hold-up at an outlet in Triq Ġużè Orlando, Birkirkara, on Monday evening.