Four first responders who arrived at the scene of Sunday’s fatal private plane crash near Raphine, Virginia, told CNN the plane left a “crater,” and they believe it impacted the ground at a very steep angle.

The first responders, who spoke on the condition they not be identified, described a grisly scene. There were perhaps four recognizable pieces of wreckage from the plane, they said. “There was nothing really bigger than your arm,” said one.

They also found signs of human remains.

Federal officials are investigating the crash of the unresponsive plane that flew near the US Capitol region on Sunday, prompting military fighter jets to rush to intercept the aircraft before it went down in Virginia, leaving no survivors, authorities say.