(FOX 5/KUSI) — Southbound Interstate 5 at the San Diego-Orange county line had slow-moving traffic throughout early Monday morning due to an incident that caused several lanes to be closed.

Incident logs from the California Highway Patrol show that officers first responded to I-5 near Basilone Road around 12:30 a.m., just north of the San Onofre Nuclear Generating Station.

Several lanes of southbound I-5 were closed for several hours, causing a traffic backup that extended for several miles toward San Clemente.

The backup was visible on several map and traffic websites.

As of the 7 a.m. hour, only two of the southbound lanes had reopened, according to the CHP's logs.

A representative from CHP Oceanside told FOX 5/KUSI that the incident is still under investigation.

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