MARIETTA — A 2006 Lassiter High School graduate who was killed in the line of duty this week is being remembered as nurturing, selfless and a “strong addition” to the east Cobb community.

Clayton County Police Officer Sean Callahan, 24, responded to a domestic call at a Motel 6 in Stockbridge on Monday. While Callahan attempted to arrest the couple in question, the male suspect ran and a chase ensued. The suspect, whose name is not being released by Clayton police, fired at Callahan, hitting him twice.

The young officer was taken to Grady Memorial Hospital in Atlanta, where he underwent surgery late Monday and died around 5:15 a.m. Tuesday.

The suspect was also fatally shot.

Callahan’s family has not spoken to the media, but a friend, a former Lassiter counselor and his swim coach have all described his death as a “tremendous” loss.

Justin Baker, who met Callahan when they were attending Mabry Middle School, said Tuesday that it may sound cliché, but this tragedy couldn’t have happened to a nicer guy.

“I don’t know anybody who defines that more than Sean,” Baker said. “I was so proud to call him an officer. He was always very nurturing and caring, very selfless and he always put others before him, and with law enforcement, his personal qualities flowed over into his professional career.”

He last saw his friend of almost 15 years a couple of weeks ago, when they talked about Callahan’s job as an officer, one he only started four months ago.

“He said he loved it and told me that he was on his own now and it’s fun,” Baker said.

He learned about the shooting from a mutual friend and was able to visit Callahan in the hospital Monday before he died.

Callahan’s school counselor at Lassiter, Millie Dawson-Hardy, remembered him as being a quiet and shy but very “memorable” and “sweet” young man who struggled a little in school but faced the challenges head-on and always stayed positive.

“We are so tremendously sad today,” Dawson-Hardy said Tuesday afternoon. “There are many of us here on the staff who remember Sean.”

She recalled him talking about studying criminal justice in college and believes that’s what led him to enroll at Reinhardt University.

A university spokesperson said Callahan attended the college’s north Fulton campus in Alpharetta between January and June of 2011, completing the basic law enforcement training course and earned his Peace Officer certification through the state of Georgia.

Dawson-Hardy hasn’t seen Callahan since he graduated from Lassiter six years ago but was proud to hear that he had become a police officer.

“We take pride in the fact that he died doing something so honorable,” she said.

Glenn Meeden, who coached Callahan in swimming in 2004 and 2005, said the former athlete was a good swimmer and swam in a number of events.

He couldn’t recall exactly which stroke was his strongest but said, “I could tell you he was a good kid and made a strong addition to the swim team and Lassiter community.”

Meeden said he heard about the shooting on the morning news but didn’t think it was Callahan until after receiving an email from his co-workers at Lassiter that a former student had died.

“As soon as I saw his picture, then I knew that’s the Sean Callahan we had there,” he said. “When you lose someone, especially in that way, it’s pretty tough. It’s a tremendous loss and our hearts go out to his family.”

Services for Officer Callahan are set for for 11 a.m.on Friday at Johnson Ferry Baptist Church in east Cobb.