TEMECULA - Fifteen-year-old Mason Gilbert had been hearing all morning that a pair of Great Oak High School twins were among the five people who died in an apparent murder-suicide on Sunday.

But there are a lot of twins at the high school. It wasn't until a friend sent him a text message - RIP Nikita and Narissa - that he knew that Nikita and Narissa Williams, 15, had been killed.

The girls were known among their classmates and teachers for their inseparability and for personalities that Mason said "were basically light in a dark place."

"It didn't really hit me at first," said Mason, a sophomore. "But then during sixth period, when I sit next to (Narissa), it hit me."

Tuesday morning was when most students learned that their classmates had died, after authorities released their names.

The Williams sisters attended Temecula schools since 2002, completing middle school at Erle Stanley Gardner and starting their freshman year at Great Oak before transferring briefly to Chaparral High School in April and finishing the year there. They returned to Great Oak this year as sophomores.

Principal Joe Balleweg announced the news Tuesday morning over the intercom and students observed a moment of silence for the girls. During the day, Balleweg said about 75 students poured into the school's career center, where counselors and psychologists were on hand to talk to students and classmates scrawled messages for the girls in colored markers on several blank sheets of paper taped to the walls.

Balleweg said a handful of Great Oak students were so upset they had to leave school, and many more spent almost the entire day in the center. Counselors also were on hand at Chaparral, where Principal Dan Kenley said the former students' deaths were not announced, but about a half-dozen students talked to counselors throughout the day.

Some Great Oak students said they planned to wear black or SRH - a skater brand the twins wore - today in tribute to the girls.

The school is also planning to hold a memorial service there Friday morning where students will be able to speak about the sisters, Balleweg said.

When Mason learned of the news on Tuesday, he went to the center, where he said about three dozen students were crying, talking to counselors and fondly remembering the twins.

"They would have wanted everyone partying instead of crying," he said. "They (students) were talking about them, but they were laughing and talking about the good times."

Mason said he returned to class, but he didn't truly feel the pain until math class, where Narissa had used her purse to sneak in candy for her classmates.

"I was like, wow," he said."That's when I left and went to the office because some of my friends had been up there all day."

By the end of the day, Mason was decorated with stickers saying "In loving memory of Narissa & Nikita 5/27/92-11/11/07" and "It don't hurt til the bones show" - a favorite saying of the girls, he said.

Great Oak senior Arin Hobbs, 17, was heading to the restroom during third period, when a mutual friend told her that Nikita and Narissa, with whom she said she ate lunch almost every day, were dead.

"I don't believe you," was Arin's response, she said.

Many of the students with whom the twins typically ate lunch were shocked and crying, said Arin, who added that she cried "all day."

Arin said the deaths were particularly hard to take because the girls were so happy and almost naive. She said that while the shootings she's heard of involved young people who were in gangs or heavy partiers, Nikita and Narissa "were so innocent."

"You don't hear about shootings where a normal teenage girl is just hanging out and she got shot," Arin said. "You usually hear of a gang fight, a gang war. You don't hear about that in Temecula."

- Contact staff writer Rani Gupta at (951) 676-4315, Ext. 2625, or rgupta@californian.com.