SOUTH DEERFIELD — Four people, including a woman who was seven months pregnant and a 9-year-old child, were severely injured and transported to Baystate Medical Center in Springfield after a crash near the Whately town line on Routes 5 and 10 on Wednesday morning.

The Deerfield Police Department, South Deerfield Fire District and South County EMS were dispatched at 5:45 a.m. for a reported head-on crash, according to Deerfield Police Chief John Paciorek Jr.

The four people — a family of three from Holyoke in one vehicle and a Sunderland resident in the other — involved in the crash suffered “major trauma” and were each taken by ambulance to Baystate in Springfield, according to Paciorek. The chief added that there were four ambulances required, as South County EMS transported a 9-year-old boy, while the Amherst and Northampton fire departments transported the other three patients.

According to Paciorek, the pregnant woman, who was a passenger in one of the vehicles, was “being evaluated for an emergency birthing process in Springfield.” When reached later Wednesday afternoon, Paciorek said the woman gave birth to a baby boy after an emergency caesarean section and the baby is currently in the neonatal intensive care unit (NICU) at Baystate Springfield.

The 9-year-old boy, he added, was being taken to Boston by medical helicopter on Wednesday afternoon.

The cause of the crash is under investigation by the Northwestern District Attorney’s Office, the State Police Detective Unit and the Deerfield Police Department, as well as the State Police Collision Analysis and Reconstruction Section (CARS).

The roadway was closed from 5:50 to 9:40 a.m.

Chris Larabee can be reached at clarabee@recorder.com.