An Amtrak train travels northbound from 30th Street Station today in Philadelphia. Amtrak's Northeast Corridor trains resumed service today following last week's deadly derailment that killed eight people and injured more than 200 others.

PHILADELPHIA — Amtrak trains began rolling between New York and Philadelphia early today, the first time in almost a week following a deadly crash in Philadelphia, and officials vowed to have safer trains and tracks while investigators worked to determine the cause of the derailment.

Amtrak officials said Sunday that trains along the busy Northeast Corridor from Washington to Boston would resume service today in “complete compliance” with federal safety orders following last week’s deadly derailment.

Company President Joseph Boardman said Amtrak staff and crew have been working around the clock to restore service following Tuesday night’s crash that killed eight people and injured more than 200 others.

At a service Sunday at the site to honor the crash victims, Boardman choked up as he called Tuesday “the worst day for me as a transportation professional.” He vowed the wrecked train and its passengers “will never be forgotten.”

Boardman said Sunday that Amtrak would be offering a “safer service.”

“We quickly made changes, and I’m grateful, he said. “I’m thankful.”

Amtrak resumed service along the corridor today with the 5:30 a.m. southbound train leaving New York City. The first northbound train was scheduled to leave Philadelphia at 5:53 a.m. All Acela Express, Northeast Regional and other services were to resume.

Federal regulators on Saturday ordered Amtrak to expand use of a speed-control system long in effect for southbound trains near the crash site to northbound trains in the same area.

Federal Railroad Administration spokesman Kevin Thompson said Sunday the automatic train control system is now fully operational on the northbound tracks. Trains going through that section of track will be governed by the system, which alerts engineers to slow down when their trains go too fast and automatically applies the brakes if the train continues to speed.

The agency also ordered Amtrak to examine all curves along the Northeast Corridor and determine if more can be done to improve safety.