DERRY, Pa. (AP) - Police say a woman pushing a stroller across railroad tracks in western Pennsylvania was struck by a train. Both she and her 2-year-old son were killed by the impact.

Authorities say the 37-year-old Derry mother and three of her children were returning from a shopping trip early Friday evening. They say she was struggling to push the stroller across the tracks when she and her toddler son were hit by a Norfolk Southern train at about 5 p.m.

The woman's two young daughters managed to dart across the tracks and were not injured.

The victims' names have not been released pending notification of relatives.

A Norfolk Southern spokesman says the company is cooperating with the investigation but declined to comment further.

The crash happened less than 100 feet from where a 15-year-old was struck and killed by a train in July.