A semi truck spilled a load of mysterious sludge across the freeway connector Monday, covering all lanes between southbound Interstate 5 and northbound State Route 15.

The closures include the center divider and the emergency lane, California Highway Patrol officer Tommy Doerr confirmed. The northbound SR-15 is shut down from just north of I-5 and the off-ramp at 32nd Street.

All lanes of northbound 15 at 32nd Street are closed. #SDCaltransAlert — Caltrans San Diego (@SDCaltrans) December 4, 2017

CHP officials said a semi truck was hauling the load of sludge from the bay. The substance originally came from the ocean and is not toxic. But the spill could pose a hazard to drivers by creating slippery road conditions, according to CHP.

A Sig alert has been issued for the area. Around 11:15 a.m., CHP reopened the left shoulder to allow vehicles to leave while crews clean up the sludge spill, according to Caltrans. No further information was currently available.

Southbound 5 connector to northbound 15 is closed. On-ramps at 32nd and Main Street are also closed as clean-up continues. #SDCaltransAlert — Caltrans San Diego (@SDCaltrans) December 4, 2017

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