OAKLAND (CBS SF) –The West Grand Avenue on-ramp to eastbound Interstate Highway 80 in West Oakland remained blocked Thursday after a big rig trailer overturned, spilling 20 tons of organic sunflower seeds onto the roadway, the California Highway Patrol said.

The trailer, the second of a double-trailer rig, was headed onto the eastbound freeway in West Oakland around 11:15 a.m. Thursday when the accident occurred, said CHP Officer Herman Baza.

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No one was injured, Baza said, and no other vehicles were involved.

It wasn’t certain Thursday afternoon why the trailer overturned, Baza said, but “it looks like speed may have been a factor,” he said.

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No information was available about where the sunflower seed load originated, or where it was headed, Baza said.

Cleanup of the on-ramp lanes continued early Thursday afternoon, said Baza, who added that the lanes are expected to reopen between 3:30 and 4:30 p.m.

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