Four people are in custody after masked suspects armed with an axe robbed a pharmacy on Tuesday morning, police say.

Just before 10 a.m., a masked man and woman rushed into Daniel’s Drug Mart on Upper Gage Avenue and screamed at a female clerk to show them where the prescription drugs were kept. The man slammed his axe into the sales counter to get his point across, police say.

The clerk motioned to where the drugs were kept, and the suspects ran off with a “large quantity” of prescription painkiller pills and fentanyl patches. The clerk wasn’t injured.

Police were called, and a short time later the suspects were found at a Mountain address. Officers were watching the home when the suspects were seen “leaving the address with bags in hand,” police say.

Two men, one woman and one male youth were arrested and charged with robbery, with additional charges on the way.

“The BEAR Unit continues to investigate as the suspects may be responsible for a number of other similar type robberies in Hamilton,” a police news release reads.

Crime linked to prescription painkiller abuse has become an increasingly large problem in Hamilton. A man with a shotgun robbed a west end pharmacy for painkillers just two weeks ago.

While violent crime overall is trending down in the city, robberies targeting businesses and financial institutions increased by 11 per cent in 2012, and “most of these robberies are committed by drug users to satisfy their addictions,” according to a report presented to the police services board last year.

From 2011 to 2012, there was a 32 per cent rise in opioid-related arrests in the city — 127 of them in 2012, up from 96 the year before.

According to statistics obtained by CBC Hamilton from the Drug and Alcohol Treatment Information System, admission rates for local opioid withdrawal programs are now the second highest in the province, behind only northern Ontario.