NEW BEDFORD, Mass. -- The Bristol County District Attorney's office said that the officers who shot and killed a man who allegedly threatened them with knives were justified in their actions.

Gerard Tierney was killed on May 14 after New Bedford police responded to a 911 call from a neighbor who said Tierney chased him with knives. Officers said Tierney refused to drop two kitchen knives. Tierney, 45, was shot by two officers as he moved toward them, holding the knives.

The officers were previously placed on paid administrative leave.

Investigators determined from interviews with witnesses and crime scene investigation that the officers acted appropriately.

"While we mourn that fact that a human life was lost, we are grateful for the courageous actions taken by the officers involved when they were faced with a decision that every police officer knows he/she may have to make some day but hopes that day never comes," said New Bedford police Lt. Jeffrey P. Silva in a statement.