An “amazing” Tewksbury mother was among the more than 50 people killed at the Las Vegas concert shooting last night, according to her sister.Rhonda LeRocque, 41, was attending the Route 91 Harvest Festival with her husband when she was shot and killed, said her sister Jennifer Zeleneski. Police said Stephen Paddock opened fire from a Mandalay Bay hotel window, injuring hundreds and killing at least 58.