PHILADELPHIA -- Nearly 36 hours after the fatal Amtrak train derailment in Philadelphia, an eighth victim has been found in the wreckage, officials said.

The Manhattan-bound train was traveling at least twice the speed limit when it came off the tracks Tuesday night, officials said. Eight people were killed and at least 200 injured in the crash.

At about 8 a.m. Thursday a canine found remains in the wreckage of the first car, Philadelphia Fire Commissioner Derrick Sawyer said. City officials did not identify the victim.

All 243 occupants of the train now have been accounted for, Philadelphia Mayor Michael Nutter said.

National Transportation Safety Board member Robert Sumwalt said Wednesday that initial data from an onboard event recorder showed the train was traveling at 106 mph as it approached a curve in the tracks. He said the engineer applied "full emergency brakes" and three seconds later, the train slowed to 102 mph, but "it was already in the curve at that time."

Sumwalt said the posted speed limit approaching the curve is 80 mph, and drops to 50 mph through the curve. He added that if positive train control -- a track technology that automatically slows a speeding train -- had been installed on Amtrak's tracks in Philadelphia, "this accident would not have occurred."

Amtrak president and chief executive officer Joseph H. Boardman pledged Thursday to install the technology.

"That will happen on the Northeast corridor by the end of the year," Boardman said.

Experts said the system must be installed on both the train and the route; the Amtrak train had it, but that stretch of track did not. A Federal Railroad Administration spokesman said Wednesday that Amtrak, which has such technology on other portions of the corridor, expects to have it in place on the stretch where the accident took place by December.

The derailment shortly before 9:30 p.m. threw the seven passenger cars around -- three landing on their sides and one partially on its roof -- violently rocking the people and luggage inside. Many of the 238 passengers aboard were forced to escape the mangled, dark cars by prying open windows and doors. Doctors said many passengers -- who later said they had felt the train was speeding -- suffered rib injuries from being thrown around or hit by flying objects or one another.

Five of the victims who died have been identified: Justin Zemser, 20, a Naval Academy midshipman headed home to visit his parents in Rockaway Beach, his family said; Jim Gaines, 48, a video software architect for The Associated Press from Plainsboro, New Jersey, the AP said; Abid Gilani, a senior vice president of Wells Fargo's commercial real estate division, the bank said; and Rachel Jacobs, chief executive of ApprenNet, an education technology company in Philadelphia. A friend, Michelle Kedem, said she had received a text message from Jacobs' family confirming her death.

Wednesday night, the fifth victim, Derrick Griffith, 42, of Brooklyn, was identified as an administrator at Medgar Evers College in Brooklyn, the school said.

Dr. Herb Cushing, chief medical officer at Temple University Hospital where more than two dozen passengers were treated, said eight patients remained in critical condition. He said he expected them to recover. "In general, we're doing much better. Most patients' conditions are either stable or better. That's very good news," Cushing said.

Nutter said the train's engineer, who was injured in the accident, met with police, but a police spokesman said he would not give them a statement and left with an attorney.

Sumwalt said the engineer, along with the train crew and passengers, have not yet been interviewed by NTSB investigators. "This person has gone through a very traumatic event and we want to give him an opportunity to convalesce," he said, adding that investigators will comb through his training and employment records.

In an interview with CNN, Nutter said the engineer was "irresponsible in his actions, and there's no excuse," unless he suffered a heart attack. But Sumwalt responded in a separate CNN interview, saying that "to make comments like that is inflammatory at this point."

Media reports and a police source identified the engineer as Brandon Bostian. The Forest Hills, Queens, resident has been with Amtrak since 2008, records show.

Dennis Pierce, national president of the Brotherhood of Locomotive Engineers and Trainmen, which represents the engineer, in a statement declined to comment on the crash, saying he would not "speculate on the actions that may have contributed to this terrible tragedy."

Investigators Wednesday continued analyzing information from the "black box" event recorder retrieved from the train with data on its performance at the time of the accident, including its speed and whether brakes were applied.

"It can give us a lot, so that will be key to this investigation," Sumwalt said, adding that the train was also equipped with a forward-facing video camera in the front car.

Sumwalt said the multidisciplinary team will examine the train's signals and operation, the condition of the track and human performance. He expected investigators to remain on the scene for about a week, then continue examining the train's wreckage at a secure location.

The train, Northeast Regional Train 188, from Washington, D.C., due into New York at 10:30 p.m., had left Philadelphia's 30th Street station at 9:10 p.m. Tuesday. It was pulled by an ACS-64 electric locomotive built by Siemens, a model first put into service last year capable of reaching speeds up to 125 mph.

The FRA said Amtrak inspected tracks in Philadelphia just hours before the derailment and found no defects.

Train service between Washington, D.C., and New York remains suspended on Amtrak's Northeast Corridor -- the most heavily traveled stretch of tracks in the United States.

With Alfonso A. Castillo