A man died Wednesday afternoon after a struggle with Fairfax County police officers who were trying to take him into custody and to bring him back to his group home, police said.

The incident began when officers were dispatched to Roundtree Park in Falls Church just before 1 p.m. on a report of a “critical missing man” who had wandered away during an outing with his program, Chief Edwin C. Roessler said at an evening news conference.

Police did not detail the man’s medical or cognitive condition or explain why he was a client of a group home.

The man was identified as Paul A. Gianelos, 45, police said, and an officer found him about a mile from the home along a commercial strip about 1:02 p.m.

The officer talked with Gianelos and called to have a caregiver come for him. But police said that before Gianelos could be reunited with the caregiver, Gianelos suddenly attacked the officer, who called for backup.

“For unknown reasons, Mr. Gianelos became physically combative,” Roessler said.

Three additional officers arrived, helped restrain Gianelos and handcuffed him. Roessler described Gianelos as being 5-foot-9 and 280 pounds, and he said that officials do not think that officers used any weapons to take him into custody. Roessler said he thought that Gianelos was unarmed.

After the struggle, police said officers called for a medic at 1:06 p.m. to treat a scrape on the man’s head, Roessler said.

When medics arrived, Gianelos collapsed into apparent cardiac arrest, Roessler said. Medics began CPR at 1:17 p.m. and took him to Inova Fairfax Hospital, where he died soon after arriving.

Police did not identify the group house where Gianelos was a client, but said it is a private, nonprofit program.

Roessler said the officer who found Gianelos is a veteran of more than 20 years and is a trained crisis-intervention officer with experience in dealing with people with mental challenges and disabilities.

“The goal of the officer was to reunite the man with his caregiver,” Roessler said. “He understands disability and agitation.”

Police did not immediately explain the nature of Gianelos’s medical emergency. An autopsy will be performed.

The death is being investigated by the major crimes division, and the police department’s Internal Affairs Bureau is investigating the incident to ensure that policies and procedures were followed.

“We are deeply saddened by his loss,” Roessler said. “This is just a tragic episode.”