Because Jet Rescue Air Ambulance is a foreign company, the Philadelphia investigation could be a bit more challenging.

NTSB investigators have recovered the engines and cockpit voice recorder (CVR) of the Learjet 55 that crashed on Jan. 31 in Philadelphia, killing at least seven people.

The crash claimed the lives of seven people and injured 24 others, but Managing Director Adam Thiel noted the forensics investigation is ongoing.