Authorities said an 83-year-old Montague woman died in a head-on crash in Deerfield Monday. Police said two vehicles collided just after 3 p.m. Celia Allen was pronounced dead at the scene. The driver of the other vehicle — Aaron Stark, 19, of Deerfield — was taken to Baystate Medical Center in Springfield with injuries not believed to be life-threatening. Neither vehicle had any passengers. The crash is under investigation.