The wreck was reported around 7:45 a.m. between westbound Exits 66 and 68, CTRoads.org said.
No one was hurt, but the crash caused a traffic jam that stretched four miles. The Department of Energy and Environmental responded to the scene because of a reported fuel leak.
Police closed the I-691 West ramp (Exit 68W) ramp Thursday morning as they cleaned, cleared, and investigated the scene.
Visit CT Roads for updates on when the ramp reopens.
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