A Waterford man who killed himself during a standoff with police Monday night was a former Marine who was struggling with post-traumatic stress disorder, his friends said Tuesday.

Many of Justin Eldridge’s fellow Marines said it was too soon to talk about the death of their “brother,” who they said was also dealing with a traumatic brain injury sustained while on tour in Afghanistan.

Eldridge, 31, was the first commandant of the Thames River Detachment of the Marine Corps League in Quaker Hill.

Robert Montminy, commandant of the Thames River Detachment, said Eldridge was a good friend and great father.

“We are all very much still in shock,” he said. “We’re still trying to deal with it. Nobody had a clue that it could lead to this.”

Montminy said he knew that Eldridge had struggled with PTSD but that Eldridge told him he was getting treatment at a Veterans Affairs hospital and was trying to turn things around.

He spoke to Eldridge about a week ago. They talked about a Toys for Tots fundraising event that Eldridge’s wife, Joanna, was organizing for Nov. 8 in Groton.

“He served his country well,” Montminy said. “He loved his kids.”

Tom Callinan, a judge advocate for the detachment, said he met Eldridge about three years ago while performing at the annual wreath-laying ceremony at Samuel Huntington’s tomb in the Norwich Colonial Cemetery.

Callinan recalled Eldridge as a natural leader. The detachment has more than 40 members, he added.

“He looked OK on the outside, but sometimes it’s below the surface,” Callinan said. “A lot of guys just don’t talk about things like post-traumatic stress. It’s very hard to digest when you see someone with so much potential, leadership die that way.”

Eldridge was married with four children. His wife helped organize a fundraiser this June to benefit the Wounded Warrior Project. While promoting the event, Joanna spoke of the struggles her husband had with PTSD and with his traumatic brain injury.

Waterford police said at about 8:53 p.m. Monday, they responded to 147 Great Neck Road after receiving a 911 call from within the residence to report that a man inside the dwelling was going to hurt himself.

Just prior to police receiving the 911 call, Eldridge posted on his Facebook page, “See you later Facebook!!!!!!!” He then posted, “Theres only so much bashing someone can take before they react.”

When police arrived, they learned that the man, later identified as Eldridge, and four children were inside the home. Police said they believed he was armed with a gun. It was not clear whether his wife was in the house as well.

Police said they could not make contact with Eldridge, so the State Police Emergency Services Unit was contacted for assistance. The state police unit also attempted to make contact with the man, with no success.

Waterford police Lt. David Burton said police told area residents that they either had to stay in place or evacuate their homes. He said only one couple decided to leave.

Burton said that around 1 a.m., the state police unit made its way inside the residence and found Eldridge dead of an apparent self-inflicted wound.

The state Office of the Chief Medical Examiner said Tuesday that Eldridge died of a gunshot wound to the head and ruled the death a suicide.

The children were found unharmed and were turned over to family members. Burton said the children did not see anything.

The incident remains under investigation by the Waterford Police Department’s Investigative Services Unit.

Jason Sechrist, a former senior vice commandant of the Thames River Detachment, said it had been months since he saw Eldridge.

He, too, remembered him as a focused individual with a good heart and soul.

“He was instrumental in getting the detachment started,” Sechrist said. “He worked tirelessly for Toys for Tots. It was important to him and it took a better part of a year to get that organized.”

Sechrist said Eldridge didn’t talk much about his time in the Marines, only mentioning that he and other Marines were shot at one time while driving a truck from one base to another.

i.larraneta@theday.com