An emotional Martha Tessmer, whose 16-year-old son was killed in a car accident three years ago, helped kick off a statewide campaign Tuesday at Fresno’s Hoover High School to call attention to reckless driving among teenagers.

The Madera mother was joined by Danica Lacy, Donovan Tessmer’s girlfriend, who was behind the wheel of car — driving too fast — when it crashed.

Together, they are helping promote “California Teen Safe Driving Week,” sponsored by Impact Teen Drivers, made up of a coalition of groups including the California Highway Patrol and California Teachers Association and funded by California Casualty insurance.

Car accidents are the leading cause of death among teenagers nationwide, killing about 5,000 each year — about 500 in California. The most frequent causes are distracted and reckless driving, including the use of cell phones and texting among teens behind the wheel.

“These kids made a lifetime of right decisions. It took only one bad decision to take his life,” Tessmer said of the July 2007 accident that killed Donovan.

Lacy was driving with four other passengers, including Donovan and two other boys in the back seat. The boys were horseplaying, the music was loud. Lacy was driving too fast on a dark, rural road when she lost control of the car, hitting a tree, then another.

The boys were ejected. Donovan is believed to have died instantly. Lacy and one of the other boys was injured.

Tessmer said she doesn’t fault Lacy: “There was no malicious intent.” The boys made a second bad decision by not wearing seat belts, and she said they could have spoken up and asked Lacy to slow down.

Lacy said the accident “changed her life forever.” In addition to losing her boyfriend, she said she had faced the possibility of criminal charges, “but nothing compares to losing someone you love.” Speaking to groups, she said, is part of her healing.

The message hit home for Hoover student Abel Reyna, 17. He isn’t driving yet, but will get his license soon and vowed to be a safe driver. He said seeing Tessmer’s pain over the loss of her son made an impact: “It’s hard to think of my mom going through the same thing.”

California Highway Patrol Chief Steve Badilla said more than two-thirds of all accidents are from distracted drivers.

Simple acts such as putting on lip gloss and using cell phones become deadly behind the wheel, said Kelly Browning, executive director of Impact Teen Drivers.