Update 4:55 p.m.: The Sacramento Bee reports that police detained the shooter after 3 p.m.

Update 12:23 p.m.: West Sacramento police tell KQED's Mina Kim that the Yolo Causeway has reopened. CHP confirms...

CHP confirms to KCBS:Yolo Causeway being re-opened.Traffic still very heavy in the area.bit.ly/kcbslive

— KCBS 740 AM/106.9 FM (@KCBSNews) April 20, 2012

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The ongoing hunt for a carjacker, who has reportedly shot at police, has shut down I-80 between Davis and West Sacramento, causing a massive traffic jam. Adding to the misery of trapped motorists, many on their way to Tahoe for the weekend: It's really hot.

The section of I-80, called the Yolo Causeway, was shut down as of 7:40 a.m. after "officers responded to reports of shots being fired near a business," according to AP. "A carjacking then occurred around the corner, and police spotted the stolen car and began pursuing it. Police spokesman Sgt. Nathan Steele says a gunman in the car fired at officers before the vehicle crashed."

Later, the gunman carjacked a pickup truck, hitting the owner on the back of the head. The Sacramento Bee reports that vehicle has now been found.

Update 12:03 p.m.

Here's a map of the area: