SONOMA COUNTY (CBS SF) — CHP issued a severe traffic alert Friday afternoon following an injury accident involving multiple vehicles including two big rigs that has shut down both directions of state Highway 37 in Sonoma County for hours.

The KCBS Traffic Twitter account posted about the incident at around 1:24 p.m.

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The 511.org Twitter account posted about the accident at around 1:40 p.m. saying traffic was blocked in both directions.

The accident on CA-37 east of CA-121 has blocked both eastbound and westbound traffic, according to CHP.

Shortly after 2 p.m., authorities confirmed that eastbound traffic on CA-37 was being diverted off at CA-121.

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Photos posted by an ambulance service showed multiple emergency vehicles including a CHP helicopter at the scene. Footage shot by Chopper 5 appeared to show one lane of traffic moving past the accident.

It took a couple of hours for tow trucks to clear the wreckage of the big rigs from the crash scene. The collision also involved two vehicles, one of which was a sport-utility vehicle.

At least one person was airlifted to John Muir Medical Center in Walnut Creek for treatment.

At around 4:30 p.m., the westbound lanes of the highway were reopened, according to KCBS Radio.

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Shortly before 5 p.m., CHP announced that all lanes had reopened. Drivers were advised to expect residual delays.