Federal investigators on Sunday recovered the wreckage of a small plane that nosedived into an eastern Arizona high school and exploded, killing all four people on board.
Firefighters cleared the way for investigators with the Federal Aviation Administration and National Transportation Safety Board by putting out hot spots that remained after the single-engine Piper crashed Friday afternoon into the empty two-story school building in the small town of Eagar.
Investigators were able to find all major structural components of the plane, NTSB investigator Joshua Cawthra said.
"The airplane was severely fragmented and there was definitely a lot of fire damage," he said.
The wreckage was being transported to a secure facility in Phoenix, where investigators would continue to comb over the charred pieces, looking for any clues to what may have caused the crash.
"We've got a lot left to do," Cawthra said. "We'll be looking at everything — man, machine and environment."
Investigators will try to determine if there were any mechanical anomalies with the aircraft as well as examine the flight plan, the pilot's history, the weather conditions at the time of the crash and if any safety related issues could have contributed.
The plane had just taken off from the nearby Springerville airport when the crash happened. It was headed to the Grand Canyon.
Earlier in the day, the plane had stopped in Wichita Falls, Texas, but Cawthra was unsure of its stops before that.
The bodies of the four people on board were also recovered and sent to the medical investigator. Apache County sheriff's Sgt. Richard Guinn said earlier in the day that authorities had not been able to determine even the gender or age of the four, but he was hopeful their identities could be confirmed by late Sunday.
Authorities declined to release the name of the plane's registered owner.
The plane had circled above Eagar two or three times before it suddenly crashed into the main building at Round Valley High School just before 2 p.m. Friday. There is no evidence of a distress call, Cawthra said.
Hours after the crash, flames continued to erupt above the building. Fire crews from nearly a dozen small towns in the region raced to battle the flames.
Officials evacuated homes in neighborhoods east and north of the school as a thick plume of dark smoke poured out of the top of the building.
There were no reports of injuries on the ground. Classes at the school are out for the summer, and Guinn said no teachers or staff were on the grounds because they work a four-day week during the break.
The school serves about 500 students in Eagar and Springerville and is about 200 miles east of Phoenix. The blaze was contained to the main school building.
Cawthra said it will be a complex job to determine the cause because of the crash site.
"There's a lot more debris," he said. "Imagine the roof of the school literally collapsing and all of the other damage from the fire. It does make it more complex, but you still work through and you gather the evidence. It just may prolong things a little bit."
A typical investigation takes anywhere from six months to a year, he said.