"With a truck that large, it's possible the driver did not know," said Sgt. Albert Gramlich of the Accident Investigation District.

Witnesses told police an industrial truck, possibly with a red cab and blue trash receptacle on the back, struck the woman, who was standing on the southwest corner of Bustleton and Cheltenham Avenues, about 9:30 a.m., Gramlich said.

There is a light at the intersection and it appears the victim was preparing to cross Bustleton, Gramlich said. Authorities were still trying to determine whether the victim stepped off the curb and whether the truck driver had a green light as he turned right from Cheltenham onto Bustleton.

Gramlich said that the victim, whose name was not released pending notification of next of kin, was struck by the side of the truck and that it was not likely there would be damage to the vehicle. There might be a streak in the grime of the vehicle where it brushed against the victim.

The woman was pronounced dead at the scene a short time after she was struck. Jeff Moran, spokesman for the Philadelphia Medical Examiner's Office, said an autopsy was scheduled for today.

Witnesses told police that they did not see the truck driver stop, slow down or speed up after the accident and that he possibly did not know that a pedestrian had been struck. Authorities said they were still trying to confirm witness reports and would canvass the area again today to try to find more witnesses.

Authorities stopped a vehicle matching the truck's description but said it was not the vehicle involved with the accident. Anyone with information about the accident is asked to call investigators at 215-685-3180.