Updated

Connecticut State Police are planning to release a report assessing the agency's response to the 2012 massacre at Sandy Hook Elementary School.

The after-action report is expected Friday. Police have not explained why it's taken five years since the shooting to complete the review.

A 20-year-old gunman killed 20 first-grade children and six educators inside the school before killing himself. He also fatally shot his mother before shooting his way into the school.

Officers from the Newtown Police Department were the first to respond to the scene. A prosecutor's report in 2013 said that nearly six minutes passed between the arrival of the first Newtown police officer and the time officers entered the school. Officers were not able to intervene before the gunman turned the gun on himself.