Update: Black Box Recovered in Train Derailment

(ABC NEWS) — Investigators from the National Transportation Safety Board are at the site of an Amtrak crash in Philadelphia today trying to determine the cause of Tuesday night’s derailment, responsible for at least six deaths, just as officials said they had recovered the train’s black box. The preliminary focus of the probe is speed, officials confirmed to ABC News today. The train’s black box — known as an event recorder — has been recovered, Philadelphia Mayor Michael Nutter said at a news conference today, and is now being analyzed at Amtrak’s operation center in Delaware. Nutter said the investigation is ongoing and will take some time. He did not offer an exact timeline. Video Link Here: http://abcnews.go.com/US/amtrak-crash-investigators-search-train-derailment/story?id=30998492 The accident happened at about 9:28 p.m. when six cars overturned and the engine separated from the rest of the train. Amtrak said there were about 238 passengers and five crew members on board. Five people died at the accident scene, while a sixth person died at Temple University Hospital, Chief Medical Officer Dr. Herbert Cushing said. Officials fear more bodies are in the wreckage. Hundreds of people were treated at area hospitals and 10 people remain in critical condition. Asked how many people were unaccounted for, Nutter said officials “did not have an accurate count on that.”