A pedestrian died after being struck by a tractor-trailer on I-95 northbound in Lexington early Friday morning.

State police say the truck was traveling between exits 30A and 30B when the driver struck a man around 3:45 a.m.

The man was brought to Lahey Hospital in Burlington and pronounced dead.

Police are working to determine a cause of the crash, including figuring out why the man was on the highway. They’re also attempting to identify the pedestrian.

Law enforcement had not filed charges as of later Friday morning.