In addition to failing to suspend the license of a driver who allegedly killed seven motorcyclists in a crash last month, the Massachusetts Registry of Motor Vehicles also ignored written out-of-state violation reports for at least 16 months, leaving tens of thousands of warnings about Massachusetts drivers to build up in a Quincy storage room, officials said Monday.

An internal review discovered the notifications from out-of-state agencies last Wednesday, and while Transportation Secretary Stephanie Pollack said RMV employees have been working nonstop to address the backlog and issue suspensions where necessary, officials still have not determined who was responsible for handling the paperwork or why processing stopped entirely more than a year ago.

Pollack and Gov. Charlie Baker, appearing at a press conference to announce what interim RMV Registrar Jamey Tesler has found since he took over last week amid an unspooling controversy surrounding the registry's role in the New Hampshire crash, said they have implemented several changes and will seek a full outside audit.

Baker admitted that the administration has "a lot of work to do to earn back" public trust.

"The RMV failed to act on critically important information that had been previously communicated by another state," Baker said. "This failure is completely unacceptable to me and to the residents of the Commonwealth, who expect the RMV to do its job and track drivers' records."

The truck driver charged with seven counts of negligent homicide in the New Hampshire crash, 23-year-old Volodymyr Zhukovskyy of West Springfield, had been arrested in Connecticut in May for allegedly operating under the influence and refusing a chemical test.

Those charges should have automatically triggered suspension of his Massachusetts commercial driver's license, officials said, but the electronic and written notification about the incident from Connecticut went unnoticed at the RMV until after the June 23 crash.

Commercial licenses are tracked in a nationwide digital database, but because of the way the RMV's system was programmed, the Connecticut referral about Zhukovskyy's arrest was "kicked out" into a queue that employees were supposed to review manually, Pollack said.

No staff were formally assigned to that job, though, so his case was never seen before the crash.

Baker said Monday that Connecticut did nothing wrong in how it handled the situation. Instead, the blame rests on the RMV, where former registrar Erin Deveney resigned last week as the problems were revealed.

The internal review found 365 additional commercial license notices "reflecting serious offenses" in the manual queue that had never been processed. Most of those were duplicates of issues handled elsewhere, officials said, and Zhukovskyy's was the only one that called for automatic suspension, but the system has been changed to ensure that situations such as his are handled.

However, the initial review under Tesler's tenure determined the problems run much deeper than the commercial license system. In March 2018, the review found, employees "stopped processing out-of-state notifications and simply sorted them into mail bins and stored them in a records room" at the Quincy's RMV headquarters.

On Wednesday — the first full day with Tesler as interim registrar — staff found 53 bins containing "tens of thousands" of communications from other states about Massachusetts driver violations ranging from running red lights to more serious matters.

While commercial license notifications go into a digital system and a voluntary electronic reporting network exists for states to notify one another about all other drivers, Pollack said most states still rely on mailing paper reports.

"We're still trying to understand why in March of 2018 people stopped processing the paper notifications entirely, but that appears to be what happened," Pollack said.

RMV employees have been working through the backlog in recent days to determine which reports warrant immediate action. As of Monday, 655 licenses have been suspended, and all additional alcohol-related violations will be weighed completely by the end of the day. The RMV also "changed how we do business" to prevent another buildup of paper or electronic reports, Pollack said.

One of the most significant steps will be a top-to-bottom review of all 5.2 million licenses issued in Massachusetts. RMV staff will compare every single driver's record to electronic records in the National Driver Registry, a federal resource, to identify any recent violations that justify suspension.

National records are typically checked when drivers renew their licenses, typically every five years, but the additional review will take place over the next few weeks as an added precaution in what Pollack called an "unprecedented" action.

It remains unclear why so many written reports when unprocessed for so long. The responsibility for sorting through paper notifications has shifted over time, Pollack said, and the outside audit will focus on establishing an exact timeline.

"We've asked the auditors to create a timeline because this responsibility has moved around over time, and that's one of the issues we need to get a better understanding of," Pollack said. "We know at one point in time whose job it was. We know that, at one point in time, it was shifted to the Merit Rating Board. But we are still really trying to understand who made which decisions about where it moved and whose responsibility it was."

Senate President Karen Spilka and House Speaker Robert DeLeo, after meeting privately with Baker, described the crash as a "tragedy" and said they wanted the RMV's review to finish before determining if there was any action the Legislature should take.

"We're anxiously awaiting to see where there may have been a failure in the system that we have," DeLeo said. "This failure resulted in some deaths, which made it all the more tragic. Having said that, I don't think we have enough information at our disposal if this is a system that requires further legislative review."

Asked if she plans to resign, Pollack said, "the governor has asked me to fix it and I'm going to fix it."

Correction: An earlier version of this story incorrectly stated the town where Zhukovskyy lived.