(Reuters) - A Florida sheriff has fired two more deputies, alleging that they failed to take action to stop the 2018 massacre of 17 students and staff at Marjory Stoneman Douglas High School, one of the deadliest school shootings in U.S. history.

The deputies, Edward Eason and Josh Stambaugh, were terminated for neglecting their duty during the Feb. 14, 2018 shootings, Broward County Sheriff Gregory Tony said on Wednesday. The decision followed an investigation into the conduct of seven deputies.

In addition to the fatalities, 17 people were wounded in the assault in Parkland, Florida. An expelled student Nikolas Cruz, who was 19 at the time, is awaiting trial on murder and attempted murder charges.

Two Broward County deputies, Scot Peterson and Brian Miller, were previously accused of neglecting their duty during the shootings. Peterson was suspended and later left the force, while Miller was terminated.

Peterson was charged on June 5 with felony child neglect and negligence after having taken cover outside the school building while the gunman went on a rampage inside. Peterson was briefly jailed but is currently out on bond.

No disciplinary action will be taken against the remaining three deputies, Tony said.

“As we conclude this final chapter for this organization in terms of this internal affairs investigation, we are now going to continue moving forward with fixing the issue that exists here in the agency related to training,” Tony told a news briefing.

The deputies’ union said it would challenge the firings of Eason, Stambaugh and Miller in arbitration.

Jeff Bell, president of the Broward Sheriff’s Office Deputies Association, said the investigation that resulted in their dismissals was tainted because it was not completed in a timely way. He said the terminated deputies were being made scapegoats for the shootings.

“Once again, the deputies and sergeants are left holding the bag for all the discipline that’s being applied,” he said by phone.

Peterson also faces legal trouble in civil court. Last May, the father one of the students killed in Parkland filed a wrongful death lawsuit against the former deputy.

Another ripple effect of the shootings occurred at the top of the department in January when newly elected Florida Governor Ron DeSantis suspended Scott Israel as Broward County sheriff, claiming he showed leadership failures at the time. DeSantis named Tony as his replacement.