Only one sheriff's deputy failed to stop the gunman who killed 17 people at a Florida high school, the Broward County sheriff said on Sunday, dismissing reports that other deputies did not enter the school during the attack as unverified.

Broward County Sheriff Scott Israel also said his department acted properly in at least 16 of the 18 calls it received before the massacre, warning that Nikolas Cruz, the 19-year-old suspect, was dangerous.

Israel rejected a call for his resignation from a state legislator and defended his department on the CNN program "State of the Union" on Sunday from criticism that deputies missed warning signs about Cruz, a former student at Marjory Stoneman Douglas High School in Parkland, Florida.