About 2 a.m. Sunday, a 28-year-old man died after his car rolled several times and ejected him on the Courtney Campbell Parkway. Witnesses told authorities another car cut off the driver.

Five people, including three teenagers, died on U.S. 301 in Thonotosassa when a man in a pickup trying to pass a vehicle slammed head-on into a car about 2:40 a.m. The pickup driver wasn't wearing a seatbelt, investigators said.

About eight hours later, a man tried to make a U-turn on Gibsonton Drive and collided with another car, killing an 83-year-old woman. Her husband, 85, was listed in fair condition Monday at Tampa General Hospital.

By late afternoon, a 17-year-old girl and her 18-month-old daughter were killed after the car they were riding in drifted off Interstate 75 and into a tree. It was unclear whether the teen wore a seat belt.

Harrison, a traffic and safety specialist who oversees Operation 3-D - a public awareness program that looks at how the sheriff's office deals with people who drink and drive - called Sunday's tally of traffic fatalities the worst in his 28-year career.

Harrison said the number of Hillsborough traffic deaths this time last year was nine. It's up to 23 this year.

Statewide, fatalities seem to have dropped, said Frank Penela, spokesman for the Department of Highway Safety and Motor Vehicles.

In 2005, the agency reported 3,533 fatalities. Preliminary numbers for 2006 show there were 3,253 traffic deaths, though that number could change as the agency verifies reports, Penela said.

Population growth, congested roads and bad weather all contribute to horrible driving conditions, Harrison said.

"But traffic doesn't cause crashes," he said. "Roads don't cause crashes. Drivers cause crashes."

The key to better driving is adjusting to your surroundings, he said.

"If conditions are worse than what you're expecting, reduce your speed," he said. "Be more considerate."

On Monday at the Florida State Fair, Tampa police Officer Randy Davis manned a booth where fairgoers could learn about safe driving.

"It's hard for me to understand the decisions people are making driving their cars," said Davis, who investigates drag racing, among other crimes. "It astounds me. This is what causes accidents."

Florida Highway Patrol Trooper Larry Coggins called the weekend the most dangerous in his three years as patrol spokesman. Drivers are too distracted, he said.

"Every single day in the Bay area, we talk about a traffic crash that has injured or killed somebody," Coggins said. "People need to do a better job of driving."

His tips: Pay attention and buckle up.

Researchers Melanie Coon and Catherine Hammer and photographer Crystal Lauderdale contributed to this report. Reporter Sherri Ackerman can be reached at (813) 259-7144 or sackerman@tampatrib.com.