Authorities say the trooper spotted a suspicious man around 3:20 p.m. in the town of Constable. It turned out to be David Sweat, one of the two convicted murderers who escaped from an upstate New York prison three weeks ago.
Sweat was taken into custody and transported to a hospital.
State police said Sweat's condition was unknown. U.S. Sen. Charles Schumer says federal law enforcement officials told him the inmate was shot twice.
The other inmate, Richard Matt, was shot and killed Friday.
Authorities had been searching for the men since their June 6 escape from a maximum-security prison about 30 miles away.