State police in Perry County say the truck was heading north on Route 11/15 in Watts Township when it veered into the southbound lanes at about 2:40 p.m. Saturday.
Trooper Adam Reed says the pickup hit a southbound car, which was then also hit from behind by another car.
Reed said in a statement that the truck driver, 69-year-old Stella Burgard of Duncannon, was killed. So were both occupants of the first car, 22-year-old Jessica Bennett of Windsor and 21-year-old Jasmine Burns of Windsor.
Two occupants of the third vehicle were taken to Hershey Medical Center with injuries that were said not to be life-threatening.