A Hazmat team was called to clean up a leaking substance from a semi-truck off the southbound lanes of Interstate 5 in Carlsbad.
The California Highway Patrol said a big rig stalled around 3:15 p.m. and pulled over onto the right-hand shoulder of the Palomar Airport Road on-ramp.
A driver passing by reported an unknown white substance leaking from one of the drums in the trailer.
When officers arrived on scene to investigate the leak, they declared it a Hazmat situation after seeing the hazardous materials placards on the truck.
Crews determined the liquid was a hazardous -- but not deadly -- cleaning substance made by Airproducts which is 80 percent water.
The Palomar Airport Road on-ramp to I-5 South was shut down for at least three hours. Traffic on the road was backed up for a time.
“At the end of the day, we just want to make sure that this substance is going to be safe and that this truck can leave out of here and be transported safely so that nobody is injured,” said CHP spokesman Jim Bettencourt.
The truck will not be allowed to leave until Hazmat crews have cleared it, the CHP said.