Federal investigators on Saturday began gathering debris from two news helicopters that collided while covering a police chase on live television and crashed, killing all four people aboard.

The investigators plan to lay out the wreckage elsewhere to try to determine the point where the two aircraft collided Friday, National Transportation Safety Board investigator Howard Plagens said.

"We're just mapping out the locations ... how things are scattered, that's our main focus," he said.

Investigators said they'll need at least another day to finish going through the debris, which was sprayed across the ground and landed atop nearby buildings.

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On Saturday, investigators allowed reporters into the crash site.

The helicopters' hulls were flipped over and squashed in two twisted heaps. The explosion blackened grass and trees. Curved metal sheets from the choppers floated upside down in a nearby pond.

The pond was laced with fuel from the helicopters, and the air was scented with burnt metal and aviation gas, NTSB board member Steve R. Chealander said.

Helicopter parts were scattered all around: a foam seat; a disembodied tail rotor; small hunks of metal colored red, orange, yellow. Some parts sprouted frayed wires as if ripped from the engine.

Investigators plan to check whether the pilots followed Federal Aviation Administration regulations.

The helicopters from TV stations KTVK and KNXV collided as both circled over the chase. Video from other stations showed white smoke trailing the choppers as they dropped into a grassy downtown park and exploded.

Killed on board the KTVK helicopter were pilotScott Bowerbank and photographer Jim Cox. On board the KNXV aircraft were reporter-pilot Craig Smith and photographer Rick Krolak. No one on the ground was injured.

Chealander said his crew will spend the next several days interviewing witnesses and reviewing maintenance records for the helicopters.

The NTSB will use a police hot line number to try to get witnesses to call in, Chealander said. Numerous people saw the helicopters drop to the ground.

Meanwhile, the man suspected of starting the chase was booked into jail on three counts of aggravated assault with a deadly weapon, two counts of theft and one count of resisting arrest.

Christopher Jermaine Jones, 23, also may be held responsible for the helicopter crash, police said.

Formal charges are expected to come later. At an initial court appearance, bail was set at $1 million.

According to court documents, Jones told officers that he didn't remember stealing two trucks, ramming a police cruiser and leading officers on a chase through Phoenix. He said he woke up as officers were trying to arrest him at his friend's house.