A state trooper was killed on I-84 near Exit 31 in Southington on Thursday afternoon, according to Connecticut State Police.

Police say Trooper First Class Aaron Pelletier, of Troop H-Hartford, was standing outside his cruiser conducting a traffic stop when he was sideswiped by a red pickup truck and killed.

They also say the driver fled the scene, but officers were able to later arrest them near Exit 39A after the truck broke down. Their identity and charges will be posted at a later time.

Officers reported that K-9 Rosso, Pelletier’s assigned K-9 officer, had accompanied him on the traffic stop, but was not injured. He was returned to the K-9 unit by another trooper.

Pelletier was married with two children and had served as a state trooper for nine years.

State police held a procession Thursday night along the highway to escort Pelletier’s body from the scene.

Connecticut State Police, Lt. Gov. Susan Bysiewicz and Commissioner Ronnell A. Higgins, of the Dept. of Emergency Services and Public Protection, held a press conference in Middletown to share details about the accident.

“Yesterday, we marked the 121st anniversary of the establishment of the Connecticut State Police. With great sorrow, I tell you that Trooper First Class Pelletier becomes the 26th Connecticut State Trooper to die in the line of duty,” said Colonel Daniel Loughman.

“Trooper Pelletier was part of the tapestry that weaves this diverse state together,” said Higgins.

Residents who live nearby also offered their condolences.

"Feel terrible about it, of course,” said TJ Calabrese.

Calabrese said he is a proud supporter of law enforcement and was heartbroken to hear about Pelletier.

"I wish people would be more careful. Something like that happens on the highway, you gotta be careful when you're going by,” said Calabrese. “It’s tragic.”

"I feel so sorry for their loss today,” said Greg Drwal, of Derby.

Drwal is a professional drone operator and took video of the scene. He said he was on his way to see his mother when he got stuck in traffic, telling News 12 his heart goes out to one officer he spoke with who seemed shaken.

"Cop just came by and said that's his partner, what happened to him. It was his longtime partner and he was by his side all the time,” said Drwal.

Gov. Ned Lamont also directed U.S. and Connecticut state flags to be lowered to half-staff effective immediately in honor of Pelletier.

He said flags should stay lowered until further notice.

Police are reminding the public to slow down and respect the ‘Move Over Law’ when it comes to emergency vehicles.

The investigation was still open as of Thursday evening.

Anyone with information is asked to contact Troop H in Hartford at 860-534-1000.