However, Israel said video showed the deputy arriving at the west side of the building where the shooting took place.
As part of the response to one of the deadliest school shootings in USA history, Broward County Sheriff Scott Israel told reporters on Wednesday that deputies that patrol high schools in the county will be equipped with rifles.
When asked Wednesday about Cruz's motive, Israel said simply, "Pure evil". "But we need to be able to defeat any threat that comes onto campus", Israel said.
Peterson was the only armed officer at the school at the time of the shooting.
Israel said the policy was implemented Wednesday morning and deputies will be required to keep their rifles locked in their police vehicle when they are not being carried.
Israel said he chose to suspend Peterson without pay pending an investigation, but Peterson made a decision to resign.
Israel said the policy is being carried out in cooperation with the county's school superintendent.
Marjory Stoneman Douglas High's school resource officer was carrying a weapon when the shooting happened last week but did not discharge his firearm.
"Certainly every school in the nation should have a school resource deputy".
Peterson was on campus, armed and in uniform during the shooting, the sheriff said.
The School Resource Officer identified as Scot Peterson has since resigned.
"I think schools as soft targets need to be fortified", Israel said. He suggested schools could be built in ways that reduce the potential for crime, and that every campus in the United States should have a resource officer. In the same event, Israel called for "sensible gun control" and told reporters: "There are certain people in this country that should not be ever allowed to have a gun".
"Years ago, I would've said that the safety of our children is dependent upon law enforcement", he said.