The troopers were shot at about 11 p.m. Friday at the barracks in the town of Blooming Grove near the New York state border. One trooper was leaving the barracks and another had just arrived for the night shift when shots were fired.
Authorities did not have a description of the shooter or shooters but said they were following several leads. The troopers' names have not been released yet.
Pennsylvania State Police Commissioner Frank Noonan said at news conference that the attack seemed to be directed solely at state police.
The shooter or shooters were still on the loose on Saturday morning, Noonan said, prompting a manhunt by police from the three states of Pennsylvania, New York and New Jersey.
This is the second fatal shooting of a state trooper in northeastern Pennsylvania in the past five years. In 2009, trooper Joshua Miller was killed while on duty after a high-speed chase ended in gunfire in Monroe County.