iStock / Thinkstock(BROWARD COUNTY, Fla.) — Authorities released new surveillance video today that shows some Marjory Stoneman Douglas High School students just as a gunman was opening fire at the Parkland, Florida, campus. The footage, which starts at 2:22 p.m. — one minute after authorities said the shooting started — shows some students walking in an outdoor passage between buildings. The Broward County Sheriff’s Office released the video. An official is seen banging on the door of Building 1, located away from where the shooting was happening. An officer then approaches the official and the two start to run.The video does not show inside the buildings, the gunman or the faces of any students.Seventeen students and staff members were shot and killed in the Feb. 14 mass shooting at Stoneman Douglas, sending shock waves throughout the nation. The suspected shooter, Nikolas Cruz, a former student, allegedly fled with students after the shooting, and later was apprehended.Cruz, 19, has been charged with 17 counts of premeditated murder in the first-degree and 17 counts of attempted murder in the first-degree. On Wednesday Broward County Judge Elizabeth Scherer entered a not guilty plea on Cruz’s behalf, after his lawyers indicated he would stand mute, or refuse to plead either innocent or guilty. Defense attorney Melisa McNeill emphasized to the judge that Cruz remains willing “at any time” to plead guilty “in exchange for a waiver of the death sentence” and instead spend the rest of his life behind bars.Watch the surveillance video below:Copyright © 2018, ABC Radio. All rights reserved.