It happened around 5:30 a.m. in the northbound lanes near the Walt Whitman Bridge in South Philadelphia.
Police said the trailer, carrying some type of construction material, spilled its load over the side of I-95 and down onto numerous container trailers parked under the highway.
State police are on the scene investigating.
Officials say to expect delays in the area.
***This story is developing. Check back with 6abc.com for updates.***