A major accident shut down a busy thoroughfare Monday morning in Santa Rosa, authorities said. The collision was reported about 9:50 a.m. in the area of Fountaingrove Parkway and Mendocino Avenue, near Highway 101 and the Old Redwood Highway, according to the Santa Rosa Police Department. The number of injuries is unknown. The northbound lane of Mendocino Avenue at Bicentennial Way is closed, as well as the Old Redwood Highway’s southbound lanes at the Mendocino Avenue off-ramp.