MONTERREY, Mexico (AP) -- A Mexican aviation official says it will take at least 10 days to have a preliminary report on the plane crash that killed singer Jenni Rivera.

The 43-year-old singer, born in California, was on a Learjet with six other people that took off from Monterrey early Sunday after a concert there. The wreckage was found hours later in rugged territory in northern Mexico. The plane appeared to have disintegrated on impact.

The U.S. National Transportation Safety Board is sending a team to help investigate the crash.

Rivera was at the peak of her career as a singer in a style of Mexican music known as grupero. She was known for her soulful voice, as well as her openness about her personal troubles.

She was recently divorced from her third husband -- former Major League baseball pitcher Esteban Loaiza. And she told reporters after Saturday night's concert that she was trying to move away from her problems and "focus on the positive." She said, "I can't get caught up in the negative because that destroys you."