A Florida sheriff’s officer who did “nothing” during the Parkland school shooting last week has resigned in disgrace, officials said Thursday.

Marjory Stoneman Douglas High School resource officer Scot Peterson was armed, in uniform and “clearly” knew there was an active shooter but did “nothing” to intervene, according to Broward County Sheriff Scott Israel.

Security footage shows Peterson “arrive at the west side of building 12, take up a position and he never went in,” according to Israel, who said the revelations made him “sick to [his] stomach.”

Israel said Peterson should have “Went in, address the killer, kill the killer.”

“After seeing video, witness statements and Scot Peterson’s very own statement, I decided this morning to suspend Scot Peterson without pay, pending an internal investigation,” Israel said. “As is his right, Scot Peterson chose to resign.

“The investigation will continue.”

The sheriff said he likely won’t release the footage unless it is subpoenaed as part of the criminal case against alleged shooter Nikolas Cruz.

Two other deputies are facing investigation, Israel said.

“I’ve restricted two of our deputies as we dig deeper into this, take statements and make a decision to see whether or not they could have done more, should’ve done more,” he said.

Accused mass-murderer Cruz killed 17 people and injured 15 more when he opened fire on the school with an assault rifle on Valentine’s Day.