Dense Valley fog creates very dangerous driving conditions.
A Sanger Unified School bus was involved in a fatal accident at Jensen and McCall Tuesday morning.
The CHP says a woman driving this silver SUV ran a red light and broad-sided the bus.
One of her passengers, 24-year old Sebastian Perez died in the crash. He was not wearing a seat belt.
Another passenger and the bus driver were hurt but both are expected to be okay.
The bus also hit another car before slamming into a pole. No kids were on board on the school bus at the time of the accident.
CHP officers say it's important drivers take extra precautions and "listen" for traffic on foggy roads.
Shawn Wills, Highway Patrol: "I can't stress enough that whenever there is any fog out there you have to slow down. The biggest thing is to slow down and be extra cautious, especially when you come to intersections."
As you can see some drivers continued to make dangerous turns despite the thick fog.
This is what it looked like on freeway 41 in central Fresno. Cars were bumper to bumper during the morning commute
City streets were also backed up.
Over 70 area schools were on foggy day schedules. One school, Oak Valley Elementary in Visalia actually cancelled classes.
Eric Cederquist, Fowler Unified Deputy Supt.: "fog caused the cancellation of buses in fowler. That's not something that you like to have happen in terms of instructional and financial standpoint however you have balance it with student safety."
Cederquist says 35-percent of the students in Fowler take the bus. The fog also caused several flight delays at FYI airport. A couple of flights had to be cancelled.
In many areas the fog didn't burn off until late afternoon. That is, if it burned off at all.