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ALAMO, Calif. - Authorities say a driver pulled over during a traffic stop on southbound Interstate 680 near Alamo has died after an exchange of gunfire with a California Highway Patrol officer Tuesday morning.

Contra Costa County sheriff's spokesman Jimmy Lee said the driver first shot the officer's partner as he went up to the vehicle.

Lee said the wounded officer was transported to a Walnut Creek hospital in critical condition.The officer was on life support, the CHP toldKRON-TV Tuesday afternoon.

The CHP officer was identified as Kenyon Youngstrom Tuesday night. Youngstrom is a seven-year veteran of the department out of the Contra Costa County area.

Lee said investigators have not clarified why the driver in a green JeepWrangler was stopped by the officers just north of the Livorna Road exit at about 8:20 a.m.

No other information has been provided on the driver.

Authorities closed the freeway through Alamofor the investigation. The northbound lanes of I-680 were reopened just before 1 p.m.; all lanes onsouthbound I-680 were reopened by 6:45 p.m.

Lee also said a Nissan Maxima and its driver they were seeking in possible connection to the incident were located. The female driver was questioned and Lee said investigators determined the woman and car had no involvement in what happened.