FAIRFIELD (CBS13) — Two on-duty police officers sustained moderate injuries in a four-vehicle accident on Highway 12 Thursday.

According to CHP Solano, the accident happened around 3 p.m. when an unmarked Sacramento police car rear-ended another unmarked police car causing a chain reaction.

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(source: Fairfield Fire)

In total, four vehicles were involved in the accident, including two civilian cars.

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The two Sacramento police officers were transported to North Bay Medical with moderate injuries and are expected to live.

Solano CHP said the two civilians involved in the accident are okay.

Highway 12 was closed for a brief period of time but is now back open.

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Police have not yet revealed the identities of the police officers involved in the accident.