Brent Thompson, a 43-year-old transit police officer;
Patrick Zamarripa, a 32-year-old police officer who served three tours in Iraq with the U.S. military
Michael Krol, a 40-year-old officer who joined the Dallas police in 2008
Lorne Ahrens, a former semi-pro football player and 14-year veteran of the Dallas police
Michael Smith, a father of two who liked to give stickers to the children at his church.