The National Transportation Safety Board has been called in to help investigate the plane crash that killed singer Jenni Rivera and six others in northern Mexico over the weekend. Rivera, 43, had performed a concert in Monterrey, Mexico before boarding a Learjet25 early Sunday morning. The flight took off around 3:30 a.m. and was reported missing 10 minutes later after airport officials lost contact with the pilots, Mexican authorities said. Rivera’s makeup artist, lawyer and publicist, as well as the flight crew are all believed to be among those killed in the crash, CBS News reports.