update: 7am OPP Advise that the highway is now completely re-opened.
The East Algoma Detachment of the Ontario Provincial Police are advising that highway 556 from highway 129 to highway 532 has been closed due to a tractor trailer blocking passage.
The highway is expected to be closed for several hours until heavy tow can arrive on scene.
The O.P.P. will distribute details and updates of the road advisory as information becomes available.