NTSB probes copter crash that killed 2 cops

David Tulis / AP Law enforcement personnel embrace early Sunday as others investigate the scene of an Atlanta Police Department helicopter crash that killed two officers aboard. By NBC News staff Federal aviation officials on Sunday were investigating what caused a police helicopter to crash on a street in northwest Atlanta, killing the two officers aboard. The officers were using the helicopter to search for a missing 9-year-old boy on Saturday night. Witnesses said the helicopter was flying low and clipped power lines as it crashed to the ground near the intersection of Martin Luther King Jr. and Hamilton E. Holmes drives, WXIA-TV reported.  The boy was found safe shortly after the crash. The National Transportation Safety Board is investigating the crash. No one on the ground was hurt. The names of the two officers were not immediately released. A witness, Ravien Walker, told Channel 2 Action News: "I noticed something falling out of the sky. It hit the power line and it hit the ground. I jumped out of my car and ran because I was really close to it. It could have fell right down on top of my car." Another witness, Darryl James, told The Associated Press, "For that time of night, there was nobody on the street for some odd reason. The helicopter hit in the middle of the street with no traffic." More content from NBCNews.com: Nanny charged in stabbing deaths of two children on New York's Upper West Side New player jumps into state elections to push education overhaul NYC crime falls by one third in wake of superstorm Sandy 'Couple more days' for fuel shortage, Bloomberg says; 'free gas' offer triggers rush Despite constant bloodshed, Mexico is ignored during White House race Capitol Christmas Tree en route to spruce up Washington holiday Video: Marathon runners racing to help out Sandy victims  Follow US news from NBCNews.com on Twitter and Facebook