MENLO PARK -- Two royal family members from Tonga who were in the country to discuss political reforms for the South Pacific island nation were killed when a teenager slammed her car into their sport utility vehicle.

Prince Tu'ipelehake, 56, Princess Kaimana, 46, died Wednesday night, according to Senter Uhilamoelangi, a distant relative and longtime friend of the prince.

The 18-year-old driver who hit their sport utility vehicle was traveling as fast as 100 mph in Menlo Park, about 30 miles south of San Francisco, highway patrol Officer Ricky Franklin said. The woman survived the crash and was arrested.

Tu'ipelehake had come to the Bay Area earlier this week to discuss politics with members of the region's Tongan community, according to Uhilamoelangi, who lives in East Palo Alto and helped arrange the visit.

Tu'ipelehake, a nephew of 88-year-old King Taufa'ahau Tupou IV, who owns a mansion in Hillsborough, about 15 miles south of San Francisco, was the leading reformist in the royal family. He was head of a national committee studying democratic reforms for the kingdom.

"His voice we'll never hear again, but his legacy is going to live on," Uhilamoelangi said. "He was a good leader because he took the voice of the people all the way to the House of Parliament and carried it all the way to the king."

San Mateo County Coroner Robert Foucrault confirmed Thursday that two members of Tonga's royal family died in the crash but would not release their names until the Tongan government made an official announcement.

The deaths stunned the Tongan community, which was just finishing celebrations of ailing King Tupou IV's birthday on July 4.

"People are very much concerned, especially the people who are pushing for change," democracy movement leader 'Akilisi Pohiva said from the Tongan capital Nuku'alofa. "I think it's a great loss to the country."

The prince had been scheduled to speak at the First Tongan United Methodist Church in San Bruno on Thursday night, but the event turned into a memorial service.

The prince's sister, Princess Mele Siuilikutapu Kalaniuvalu Fotofili, sat on the stage crying throughout the service, attended by about 70 people who sang hymns and talked about the prince.

"He tried to keep the connection with the Tongan people in America," Rev. Kalatini Ahio said. "He wanted to share what was going on in Tonga with the Tongan people."

San Bruno was supposed to be the first of many stops for the prince at Tongan communities in the United States on this trip. He was scheduled to travel to Seattle after visiting the Bay Area.

New Zealand Foreign Minister Winston Peters praised Prince Tu'ipelehake's efforts at reforming Tonga's political system and said it was a tragedy that he died while traveling to the United States to seek out opinions of Tongans.

"He pursued this goal with sensitivity and perception, mixed with a strong determination to achieve progress," Peters said in a statement. "This earned wide respect in New Zealand as well as in Tonga, where he was often called the Prince of the People."

A large contingent of family members, friends and government officials traveled from Tonga to Redwood City to assist with the identification of the victims, Foucrault said.

Vinisia Hefa, 36, of East Palo Alto, who was driving the red Ford Explorer carrying the prince and princess, also was killed, the California Highway Patrol said.

Hefa's aunt, Tina Penisoni of East Palo Alto, said her niece had been secretary for the royal couple back in Tonga before coming to California about five years ago.

"They are very nice people," Penisoni said. "They liked to be like normal people. But Tongan people, we always treat them like the royal couple."

Edith Delgado, 18, the driver of the car that struck the Explorer, faced arraignment Friday afternoon in San Mateo County Superior Court on three counts of vehicular manslaughter and engaging in a speed contest, authorities said.

Delgado, who received her license in February, was racing another vehicle when she slammed into the driver's side of Hefa's car, causing it to swerve across several lanes before tumbling to a stop on its roof, Franklin said.

Delgado, who was not injured, was held in lieu of $300,000 bail.

Tonga -- a 170-island archipelago about halfway between Australia and Tahiti -- has a population of about 108,000 and an economy dependent on pumpkin and vanilla exports, fishing, foreign aid and remittances from Tongans abroad.

Now the last monarchy in the Pacific, Tonga has been a Polynesian kingdom and a protectorate of Britain, from which it acquired independence in 1970.

About 37,000 U.S. residents identified themselves as at least part Tongan in the 2000 Census; 15,000 of them live in California.