Christopher Goodell, 32, an officer in Waldwick, N.J., was using radar equipment and was parked on the shoulder of Highway 17. The collision pushed his cruiser into a retaining wall.
Bergen County Prosecutor John Molinelli said the truck driver, Ryan Cumberbatch of New York City, apparently swerved to avoid something in the road. Cumberbatch called 911 immediately after the crash.
"I'm not going to say whether he lost control of the vehicle at this point," Molinelli said. "We're still figuring out exactly why he was in the shoulder area."
Highway 17 is a busy road connecting with the New York Thruway at the state line and used by many trucks heading to and from the New York City area. Cumberbatch was carrying a load of produce for JB Hunt.
Goodell, the second New Jersey police officer to be killed on duty this week, was a former Marine and had been with the department for five years. Molinelli said he was an experienced radar officer and Waldwick Police Chief Mark Messner called him "an outstanding and proactive officer."