UPDATE, Sunday, 4 p.m.: More details have been provided by Massachusetts State Police.

» A new story has been posted

Updates a story posted Sunday at 6:35 a.m.

SPRINGFIELD — A 23-year-old Springfield man was pronounced dead early Sunday after he was shot by a Massachusetts State Police trooper during an altercation at 12:20 a.m. A female passenger in the vehicle was treated for injuries and released.

State police spokesman David Procopio said the man was shot when he either struggled with the trooper or drove his car at the officer. None of the people involved in the incident have been identified at this time.

According to Procopio, the trooper stopped the suspect's vehicle in the southbound lane of Interstate 91 near Exit 8. During the course of the stop, the male driver of the car became agitated and combative with the trooper, Procopio said.

State police provided two versions of events: An initial press release indicated the shots were fired after a struggle between the trooper and suspect, while a subsequent release said the suspect returned to his car and began driving toward the trooper, at which time the trooper drew his weapon and fired.

The driver and his 22-year-old female passenger, also a Springfield resident, were transported to Baystate Medical Center by ambulance. The driver died from his wounds, while the woman sustained relatively minor injuries and was treated and released. Authorities did not specify the nature of her injuries.

"It would be inappropriate to comment on additional details, including the reason for the initial motor vehicle stop or the exact sequence of events that led to the trooper to fire his weapon," Procopio said in a satement.

The office of Hampden District Attorney Mark G. Mastroianni is investigating the fatal shooting.

The trooper involved in the incident is a 2012 state police academy graduate who's assigned to the Springfield barracks. As is State Police policy, he has been placed on administrative leave.