MANATEE -- Ten detectives commandeered a Manatee School for the Arts office Thursday as they worked to solve the shocking slaying of teacher Kenneth Ellis.

The North Port Police detectives were part of intense activity at the Palmetto school Thursday as students and staff struggled to cope with the loss of part of their school family.

Ellis, 61, a teacher and martial arts instructor, was shot in the chest after opening his front door at 10 p.m. Tuesday in the foyer of his North Port home. Although first responders found some vital signs when they arrived, Ellis was pronounced dead soon after at Sarasota Memorial Hospital in North Port, police said.

There have been no significant leads or arrests yet as law enforcement has just begun to dive into the case, which included Thursday’s interviews with students and staff at Manatee School for the Arts, said North Port police Capt. Robert Estrada.

“We are digging into Mr. Ellis’s life,” Estrada said. “We are interviewing students at the school. We need to talk to his family, his friends and find out what his hobbies were and what he did outside of work. We hope to get some leads from this.”

Nothing is being ruled out yet, Estrada said.

“He could have been targeted or it could have been a random act, or they might have gone to the wrong house,” Estrada said. “We just don’t know. We are in the early stages of this investigation. We are building leads.”

In North Port on Thursday, police used a canine to search the area around Ellis’ home, which was released back to the family late Thursday afternoon. Two police officers were assigned to keep watch near the house, which still was considered a crime scene, overnight.

Based on interviews with Ellis’ widow, Elizabeth Materska-Ellis, the doorbell at their home rang at about 10 p.m. but no one appeared to be there when they looked out their windows. They both moved to the front door, which is glass, and Ken Ellis opened it with his wife slightly behind him, Estrada said.

The shooter did not exchange words with Ellis before shooting, Estrada added.

The suspects, who were described by Elizabeth Ellis as wearing all dark clothing and masks, ran from the house and appeared to flee in a dark-colored four-door sedan, according to police.

At Manatee School for the Arts Thursday, school officials began working on a memorial service for Ellis featuring music and art, with date and location to be announced.

Many tearful students showed up at assistant registrar Theresa Quick’s desk, where they found understanding.

“Mr. Ellis was an amazing mentor and encourager of all the children,” Quick said. “He had such a calmness.”

Students began a memory wall, writing comments for Ellis on sheets of white paper that stretched from floor to ceiling and spread through the halls. One of the most touching entries was from ninth-graders Justine Ulrey, 17, and Tiana Leighton, 16, who drew hands with students’ names on them.

“We are laying our hands on him as a final goodbye,” Justine said.

Someone wrote, “We’ll miss you Master Ellis. Everyone seems devastated. It’s horrid.”

Ellis taught tae kwon do to more than 400 students at Manatee School for the Arts. In talking to those students Wednesday about Ellis’ slaying, assistant principal Terry Devine had made this statement to them: “It’s time for the black belts to step up.”

On Thursday, the school’s 25 black belts were leading classes on their own.

A tearful Devine replied, “They stepped up.”

Since Devine’s name was listed with police as first contact in emergencies, police drove to his home in Parrish at 2 a.m. Wednesday morning to wake him up with the news of what had happened.

He asked to see their badges. “I had to make sure it was true,” he said. “It slowly became real.”

Devine waited until 6 a.m. to call Principal Bill Jones, who said, “Say again.”

Later that morning, Jones, Devine and other school leaders planned how to deliver the news that Ellis was gone, bringing teachers and staff in first, then students class by class.

Ellis’ 400 martial arts students were brought in first.

“I couldn’t look at the kids’ faces,” said Devine, who delivered the news to them. “I learned as a musician how to cope with nervousness and I stared at the back wall as I told the kids,‘We have some bad news. Master Ellis has passed away. He was a victim of a homicide.’”

Jones, who was in the theater that moment, said he will never forget big, strong 11th- and 12th-graders breaking into sobs.

James Kisacky, 18, was in Ellis’ martial arts class since seventh grade. He’s now a senior and a black belt.

“He taught us self-defense with the hope that we’d never have to use it, but if we did we’d know how to do it right,” Kisacky said. “I was really shocked by it. How could it be him? He was the nicest person you’ll ever meet.”

Ellis gave his students life lessons, Kisacky said. The last lesson Kisacky got from him was about how some people want money but refuse to work for it.

“He was always listening to CDs on how to live your life to the fullest,” Kisacky said.

Jones, who hired Ellis as one of his original faculty in 1998, said he knows the shooting happened instantly.

“Ken had the ability to quickly assess a situation and react,” Jones said. “This must have happened fast.

“I am as stymied as anyone,” he added. “I can’t imagine he had any enemies. Was it a random shooting or a gang initiation? You can conjure up any wild idea. We have no clue. All we know is that we are all devastated.”

-- Paradise Afshar, Herald staff reporter, and the North Port Sun, contributed to this report.