Seven people were taken to the hospital with minor injuries after a MBTA bus rear-ended another one Tuesday near the Ruggles T station in Roxbury, authorities said. The first bus was waiting at a light shortly before 4 p.m. The second bus, moving at a slow speed, crashed into the first, said MBTA spokesman Joe Pesaturo. Boston Emergency Medical Services spokesman Nick Martin said six passengers were transported. The woman operating the bus that was rear-ended was takento the hospital with back pain, Pesaturo said. The operator of the second bus will be cited by MBTA Transit Police for following too closely, Pesaturo said.