Updated

Two car crashes that killed a total of 11 people on Sunday occurred more than 2,000 miles apart, but bore one terrifying similarity — they were caused by drivers barreling the wrong way down highways.

Five people, including four University of South Florida fraternity brothers, died in the crash in Tampa, Fla., and six people, including four relatives, died in a pre-dawn wreck on a freeway in Pomona, Calif. Police arrested a 21-year-old female driver on suspicion of felony driving under the influence and felony manslaughter in connection to the California deaths.

While wrong-way crashes occur relatively infrequently, accounting for only 3 percent of accidents on divided highways, the fatality rate for wrong-way collisions is roughly 27 times more than other types of accidents, according to a 2012 report by the National Transportation Safety Board.

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On average, 360 people died annually in roughly 260 fatal wrong-way collisions, a phenomenon first studied by the federal agency in 1968 during its investigation of a multiple fatality wreck near Baker, Calif.

Driver impairment by alcohol was identified by investigators as a factor in 60 percent of fatal wrong-way collisions, according to the NTSB report. Furthermore, more than half of those wrong-way drivers had blood-alcohol concentration at or above 0.15, more than double the rate of impairment in most states.

Other key findings within the NTSB study included that drivers over the age of 70 constitute about 15 percent of at-fault drivers in wrong-way wrecks and that the primary origin of wrong-way movements is entering an exit ramp.

“Other mechanisms resulting in wrong-way movement include making a U-turn on the mainline or using the emergency turnaround through the median,” the report found.

Seventy-eight percent of wrong-way collisions occur between 6 p.m. and 6 a.m., and a disproportionate number of them occur on the weekends. Most wrong-way collisions take place in the lane closest to the median, according to the report.

During Sunday’s fatal crash in southwest Florida, the driver of an SUV was heading south in the northbound lanes of Interstate 275 in Tampa around 2 a.m. when the driver collided head-on with a Hyundai Sonata. Authorities said the SUV burst into flames and the unidentified driver died at the scene.

Florida Highway Patrol Sgt. Steve Gaskins said all four victims in the second car also died at the scene. Authorities said they were all males in their early 20s. They were identified by university officials as Jobin Joy Kuriakose, 21; Ankeet Harshad Patel, 22; Imtiyaz “Jim” Ilias, 20; and Dammie Yesudhas, 21.

“Our hearts are heavy at the loss of such bright, energetic and optimistic young people who had promising futures ahead of them; to have their lives cut tragically short betrays our sense of fairness and security,” University of South Florida President Judy Genshaft said in a statement. “Now is the time when our faith and the support of those closest to us can sustain us, and should in tribute to their spirit of friendship and brotherhood.”

The highway was closed for several hours and re-opened around 7 a.m. The accident remains under investigation.

Meanwhile, in California, authorities said 21-year-old Olivia Culbreath of Fontana was arrested on suspicion of driving under the influence and manslaughter after being pulled from a badly mangled Chevy Camaro on State Route 60.

California Highway Patrol Officer Rodrigo Jimenez said the crash scene in the suburb east of Los Angeles was horrific. Two people in a Ford Explorer — Gregorio Mejia-Martinez, 47, and Ester Delgado — died at the scene, said Los Angeles County coroner's Lt. Fred Corral.

Two other family members in the SUV — Leticia Ibarra, 42, and Jessica Jasmine Mejia, 20 — were declared dead at a hospital. All four were from Huntington Park, Calif.

Two additional victims were passengers in a Chevy Camaro that authorities said was driven by Culbreath. Her sister, Maya Louise Culbreath, 24, of Rialto and Kristin Melissa Young, 24, of Chino were declared dead at the scene, Corral said.

Authorities said Culbreath — who, according to witnesses, was speeding up to 100 mph — was traveling north in the southbound lanes of State Route 57 before transitioning east in the westbound lanes of State Route 60, where the collisions began.

The Associated Press contributed to this report.