Police has made an appeal to people contact them if anyone has any information about the incident.
"The Avenue is a busy road and detectives are continuing to appeal to anyone who may have seen anything suspicious in the area on Monday evening to contact them. Anyone who may have dash-cam footage of the area which may assist police is also asked to come forward," it said, adding that no arrests have been made in the case so far.
Detective Superintendent Tariq Ali also held a press conference to reassure the local residents.
"They were a really nice, friendly couple and they've become popular in the area since they took over the pharmacy," one of the couple's neighbours said.
The couple's home is close to their pharmacy, which they ran for around three years. Both the home and work premises are now the focus of intense police searches.