By Joseph Ax

NEW YORK (Reuters) - A CSX Corp freight train derailed on Wednesday morning in New York City's Bronx borough, suspending northbound Amtrak service from the city for hours but causing no injuries.

Video footage from an NBC affiliate's helicopter showed several cars sitting across the tracks, with at least one on its side.

Rob Doolittle, a CSX spokesman, said a CSX train derailed eight cars around 9:15 a.m. in a rail yard in the Bronx. Seven of the cars were empty, and one contained lumber.

CSX crews were on scene and developing plans to get the cars back on the tracks, but there is no timetable for completing the work, Doolittle said. No one was injured in the accident.

"Safety is CSX's highest priority, and our goal is zero accidents," Doolittle said. "CSX apologizes to Amtrak passengers and any others who have been inconvenienced by this event."

Amtrak, which uses tracks adjacent to the accident site, suspended service between New York City and the northern suburb of New Rochelle following the crash. Partial service with delays up to 90 minutes was restored by 12:30 p.m.

Amtrak's Northeast Corridor, which runs from Washington, D.C., to Boston, is the busiest rail line in the United States.

The train derailed in the Hunts Point neighborhood of the Bronx, about nine miles (14 km) north of midtown Manhattan.

(Reporting by Joseph Ax and Laila Kearney; Editing by James Dalgleish and Andrew Hay)