it happened on interstate 580 in oakland at harrison avenue near grand. traffic backed up for hours as authorities investigated last night. the chp tells us people in a dark gray suv and a maroon suv exchanged gunfire. one of those bullets hit the 8-year-old boy in a third car. the chp says one or both of those vehicles may have exited at park street. if you have any information you are urged to call the chp tip line. that is 707-917-4491. >>> back to the weather. that excessive heat warning telling you about goes into effect at 11:00 this morning. pg&e says it is preparing for stress on the grid. the utility says it has extra workers, extra equipment mobilized in cities where triple digits are expected today. pg&e says it is not anticipating widespread power outages nor public safety power shutoff but warns as always, could be isolated issues. pg&e is asking people across the bay area to limit their power usage this weekend to relieve stress on the grid. cinthia, though, says it will be hot. so people are going to need their a.c., if they even have it. >

here is the map at harrison avenue, near grant.has been closed for more than four hours. >> you mentioned it. sadly that little boy is in great condition tonight. nbc bay area's gia vang is in oakland. you are out there with the latest,? >> reporter: as you said, late tonight, chp did confirm that the boy was taken from highland hospital two children's hospital in great condition, and this, all happening, as this is still happening over my shoulder. so, you can see all of those red lights, those are the tail lights of cars on 580, heading eastbound. there's still so much traffic out here, and they don't look to be moving very much. so, this is on telegraph and the 580. as this investigation had begun for the shooter's tonight. >> confusion among thousands of diverted drivers on eastbound 580 shut down by chp. later, an investigator going from come to town, taking a closer look at shell casings. this is in oakland, near the grand avenue exit, because at around 6:30, friday evening, gunfire rang out. >> there were a lot of shots, we