A man held up a shop in Cospicua on Saturday afternoon and made off with an undisclosed amount in cash.
The case took place in Triq l-Oratorju at around 1.15pm, the police said.
The man, who was allegedly armed with a knife, ran off after the cashier, a 61-year-old woman from Marsaxlokk, handed him the money. No one was injured.
In a statement later in the day, the police said that the alleged thief was arrested in Cospicua, and was taken to the Police Depot.
The major crimes unit and district police are investigating.