HARTFORD, Conn. — After the 2012 school massacre in Newtown, Conn., police officials not involved in the investigation and “dignitaries” were allowed into the building and potentially contaminated the crime scene by stepping on bullet casings and glass shards that had yet to be processed as evidence, according to a report state police released Friday on their response to the mass shooting.

The report concludes state police handled the response effectively, but it recommends improvements to protecting crime scene integrity, dealing with victims’ families and other issues.

A 2013 report on the response by Newtown police said that department responded rapidly and followed policy.

Gunman Adam Lanza killed his mother at their Newtown home before shooting his way into Sandy Hook Elementary School on Dec. 14, 2012, and killing 20 first-graders, six educators and himself.

“The unprecedented nature of this incident posed numerous challenges,” the state police report says. “The unique dynamics of this tragedy tasked the agency’s resources and tested the capacity and capabilities of individuals and units alike.”

One recommendation is to limit crime scene access to authorized personnel. The report says “uninvolved” state police command staff, members of outside agencies and “dignitaries” were allowed into the school in the hours and days after the shooting, potentially contaminating the crime scene and “unnecessarily exposing personnel to the disturbing scene.”

“Relevant evidence was stepped on, including bullet casings and glass shards, which had yet to be processed and properly documented,” the report says.

The report also recommends training and developing a checklist for notifying families of the deaths of their loved ones.

In Newtown, troopers notified the families of the victims “professionally and with compassion,” but some mistakes were made, the report says.

In one case, a trooper did not know the correct relationship between a victim and the family member he was notifying, it says.

Establishment of a statewide family liaison program also is recommended.

After the shooting, family liaison officers were assigned to each victim’s family and were critically important to coordinating resources to the families, the report says.

The report urges state police officials to consider mandatory counseling for major crime detectives and other personnel who regularly deal with traumatic situations.

A state police spokeswoman said many of the recommendations already have been implemented or are being implemented.