The woman later shot herself.

The police said the incident occurred on Thursday in a pharmacy distribution centre in Perryman, near Baltimore.

"The attacker, Snochia Moseley, 26, died from a self-inflicted gunshot wound," reported BBC.

The exact cause of the attack is still not known.

A source close to the investigation told CNN the woman was a disgruntled employee.  

Three people were injured in the incident.

The police said they found the attacker in a critical condition.

She later passed away in a hospital.

She owned and had registered the handgun, and had taken several magazines of ammunition with her, police was quoted as saying by BBC. 

Image: Google Images.