Mayor Cherelle Parker said five people are still hospitalized following a fatal medical jet crash in Northeast Philadelphia, three of whom are in critical condition.

NTSB investigators found the Learjet 55's cockpit voice recorder Sunday. The agency said it was 8 feet down at the site of initial impact. The death toll is 7, with 22 injured.

Investigators have also located the aircraft's black box, CBS reports. It could provide clues into the cause of the crash.