ANAHEIM ( — A 300-foot gravel spill made a mess of the westbound 91 Freeway in Anaheim Thursday evening.

All but one lane of the freeway was closed after the spill, authorities said.

READ MORE: Pasadena Implements COVID Vaccine Mandate For Bars, Large Outdoor Events

The spill occurred around 7:25 p.m. near where the westbound 91 and northbound 57 Freeway meet.

The cause of the spill is under investigation.

READ MORE: DEA: Prescription Pills For Sale Online, On Social Media Often Laced With Deadly Dose Of Fentanyl

It was unclear how long it would take to clear traffic in the area.

Officials said they were hoping to have all the lanes cleared by 8:45 p.m. but reporting in Sky 9, Stu Mundel said, “that sounds to be very optimistic.”

MORE NEWS: School Bus Involved In Crash In Compton

For the latest traffic information, listen to KNX 1070.