U.S. transportation officials have confirmed that Mexican-American music superstar Jenni Rivera was killed in a plane crash in northern Mexico early Sunday.

The National Transportation Safety Board says the Learjet carrying Rivera and six others crashed at about 3:30 a.m. local time Sunday, about 110 kilometers south of Monterrey, Mexico. It says all aboard were killed.

The agency says the plane crashed “due to unknown circumstances.”

The NTSB says it has dispatched a team to help Mexican authorities investigate. It says its experts include advisors from the Federal Aviation Administration and Learjet, and investigative staff specializing in airplane airworthiness and flight crew operations.

Rivera had given a concert in Monterrey on Saturday.

Mexican authorities say the wreckage of the plane was discovered outside Monterrey Sunday. She was traveling to Toluca, near Mexico City.

Transportation and Communications Minister Gerardo Ruiz Esparza told Mexican television that the crash site is spread out over a wide area and “there is nothing recognizable.”

The 43-year-old California-born Rivera — the mother of five children — combined nortena, banda and other musical styles to sell 15 million records. She was nominated three times for a Latin Grammy award and won several Billboard Latin Music Awards. She was also a popular personality on Spanish television and had appeared on reality television shows.