CENTER TWP — A 25-year-old woman was seriously injured early this morning when she apparently walked into the path of a garbage truck backing up off Route 308, authorities said.

A medical helicopter later flew Sarah Archer of Butler to Allegheny General Hospital in Pittsburgh following the 5:10 a.m. crash. Her condition was not immediately known.

State police said the Waste Management truck hit Archer while driver Clyde Adams, 51, of Slippery Rock was backing up from Route 308 onto Pinewood Lane.

Adams told authorities he was making rounds and never saw the woman, even on the truck cab backup camera.

“The driver said he thought he hit an animal,” said Chief Greg Brewster of the Unionville Volunteer Fire Department. “Then he heard someone yelling.”

Archer was screaming in pain when emergency crews arrived. She complained of heart pain and appeared to have injuries all over her body, especially on her right arm and left leg.

A Butler Ambulance Service crew treated the woman while firefighters set up a landing zone in a nearby field for a LifeFlight helicopter.

Archer was sedated before being wheeled from a stretcher onto the helicopter and flown to Allegheny General.

Police said their investigation continues.

Waste Management spokeswoman Erica Deyarmin said this morning that the company is “working in cooperation with local authorities” in the investigation but declined further comment.