Haskins was walking on I-595 in Broward County "for unknown reasons," Lt. Indiana Miranda of the Florida Highway Patrol told NPR in an email.
Haskins was hit by the truck as he tried to cross westbound lanes, Miranda said. He was pronounced dead on the scene.
The fatal crash, which is an active traffic homicide investigation, was reported at 6:37 a.m., Miranda said.
He was "walking on (the highway) for unknown reasons" when the incident happened, the patrol said in a news release.
Details about what led up to that weren't immediately available. In recent days, Haskins had been in South Florida working out with some Steelers teammates,
as captured in Instagram stories from Haskins and Steelers running back Najee Harris. News of Haskins' death drew statements of shock from around the league and beyond