The NTSB is investigating the crash of a helicopter that killed a toddler and three crew members.
The chopper apparently hit the guy wire of a tower serving radio station WBIG(AM) in Aurora, Ill.
This Chicago Sun-Times story includes graphics of the area.
Among points to be determined will be whether the tower was lit. An NTSB investigator was quoted saying it was not lit when he arrived, though the lighting could have been knocked off by the helicopter.