The Philadelphia news helicopter that crashed in the New Jersey Pine Barrens this week plummeted into the thick woods “at very high speed,” before it broke apart and caught fire, killing a photojournalist and the pilot, a federal crash investigator said Friday.

ABC 6’s chopper was returning to its base at Northeast Philadelphia Airport on Tuesday night from an assignment photographing Christmas lights at the Jersey Shore, Todd Gunther, an investigator with the National Transportation Safety Board, told reporters near the crash site in Wharton State Forest.

Photographer Christopher Dougherty, 45, and pilot Monroe Smith, 57, were both killed.

They were the only two on board.

“The aircraft hit at very high speed, and after striking the trees, it fragmented,” Gunther said, adding the damaged aircraft “was subject to a post-crash fire.”

There was no in-flight fire or explosion before the crash, investigators determined.

The main rotors and tail rotors were both damaged, indicating they were still spinning when they smashed into the trees, Gunther said.

The helicopter, a 2013 American Eurocopter AS-350A-STAR, had power at the time of the crash and its transmission was functioning.

There is no indication the pilot broadcast any sort of emergency warning, Gunther added.

The chopper made two previous flights on Tuesday before plummeting into the woods in Washington Township around 8 p.m.

Investigators are still looking for anything that may have either contributed to or caused the crash, which occurred on a clear, cold night, Gunther said.

Debris from the crash stretched for 200 yards — twice what was originally calculated.

The wreckage — including the nose, tail and both sides of the helicopter — is being transported to a secure facility where it’ll be reassembled to assist in the investigation.

The NTSB may not conclude its investigation for another two years, Gunther said.

With Post wires