(HOUSTON) -- Four people, including a child, were killed when a helicopter crashed into a radio tower in Houston, officials said.
The crash happened just before 8 p.m. Sunday when a private aircraft struck a radio tower in Houston's Second Ward, Houston police said.
All four people on the helicopter were killed. No one on the ground was injured, officials said.
No homes or structures were impacted except for the radio tower, police said, but a fire that erupted from the crash spanned two to three blocks.
Houston Fire Department officials extinguished the fire after the crash.
Houston police Lt. Jonathan French said Monday he was thankful no one on the ground was hurt.
"We want to keep the families and our victims in mind right now. This is a horrible tragedy," he said, adding, "This could have been much worse."
The crash is being investigated by Houston authorities, the National Transportation Safety Board and the Federal Aviation Administration.
The helicopter was operating as an air tour flight, according to the National Transportation Safety Board.
The cause of the accident remains under investigation.