Nearly a half-hour after Nikolas Cruz dropped his rifle and fled Marjory Stoneman Douglas High School, police thought they were seeing him live on security cameras, still in the building. They were actually seeing images tape-delayed.

The Broward School District’s security cameras did not show real-time video for police, complicating their efforts to track and pin down the shooter, the South Florida Sun Sentinel has learned.

“They are monitoring the subject right now. He went from the third floor to the second floor, the third to the second floor … They’re monitoring him on camera,” an officer said on radio transmissions recorded by Broadcastify, an audio streaming website, at 2:54 p.m. In fact, Cruz was already long gone — he had escaped the school’s freshman building 26 minutes earlier and was sitting at a McDonald’s a mile away, a timeline released by the Broward Sheriff’s Office shows.

The video images were “delayed 20 minutes and nobody told us that,” said Coral Springs Police Chief Tony Pustizzi.