Three people were killed overnight in a shooting at a distribution centre for a US pharmacy chain.

A law enforcement official in Maryland with knowledge of the shooting stressed that the number of dead is based on preliminary information.

Harford County Sheriff Jeffrey Gahler has said that a suspect was taken into custody and was in critical condition.

Gahler said it appears there was only one weapon, a handgun, that was used and there were no shots fired by responding law enforcement officers.

The Harford County Sheriff adds that multiple people had been killed and wounded in the shooting, without giving any other details on casualties.

[Source: TVNZ]