Aria Karina Curad Mallari had a lot to be happy about Friday afternoon as she sat behind the wheel of her Honda Civic in rush-hour traffic on Interstate 75.

The 17-year-old had just finished her first set of summer classes at the University of Florida, where she was getting a head start on a pre-med degree. At home in Pinellas Park, a celebration awaited as her mother and brother prepared a feast of barbecue and Filipino food. It was supposed to be a birthday party. On Wednesday, Mallari would have turned 18.

But something happened as she drove south on the interstate through Wesley Chapel.

At about 5:40 p.m., Mallari lost control of the car, veering onto the left shoulder, through the grassy median and into the northbound lanes, according to the Florida Highway Patrol. The car split in two and caught fire as it collided with two other vehicles.

Mallari was seriously injured and flown to St. Joseph's Hospital in Tampa. She died during the night.

Two others were injured. Kyle Eugene Mansfield, 25, of Hernando was taken to Florida Hospital Zephyrhills with serious injuries after Mallari's car collided with his Chevy pickup, troopers said. Christine Penner, 46, of Largo, was treated at the scene for minor injuries after her Ford Ranger was also struck.

The cause of the crash, which closed the northbound lanes of I-75 for several hours Friday night, remained under investigation Saturday.

John Mallari was barbecuing in front of his Pinellas Park home when he got the call. A few hours later he lost his sister, whom he called his best friend.

"She was the sweetest girl," he said. "We were always together whenever she was here."

Born in the Philippines, the siblings moved to the United States in 2004 with their mother, who relocated for a new job. Aria was 10 then. Over the years, John, now 23, watched as his sister grew into a studious young woman who set high goals for herself. An A-student, she had just recently graduated from Dixie Hollins High School. She wanted to become a doctor.

"She was the best sister I can ask for," he said. "I miss her."

Times researcher Natalie Watson contributed to this report.