MEDFORD - Police are investigating what led to a shooting that killed four people inside a Medford pharmacy this morning.

Investigators say someone entered Haven Pharmacy around 10:30 a.m. today and attempted to rob the store. They say something went awry, leading to the shooting that killed two employees and two customers.

The pharmacist, who was not at the store at the time of the shooting, was hospitalized with chest pains after learning about the incident.

A former employee said that the owner always instructed the employees to cooperate with a robber to avoid an incident like what transpired today.

Police say they are still investigating and have not arrested anyone yet.