Hours before authorities took a Bucks County man into custody after he barricaded himself inside a Southampton house where three people were later found dead, neighbors said they saw him standing at the front door holding a butcher’s knife, wearing only underwear and with blood visible on his body.

Authorities have not publicly identified the man or released the names of the three people whose bodies were found after an hourslong standoff inside a two-story brick home at 26 Heather Road on Monday night.

Investigators have said little about the incident and have not disclosed the cause of the deaths, which were discovered after police were called to the home for a wellness check and encountered a man armed with a knife.

David Deleo, 41, was shoveling snow from his driveway when Northampton Township police arrived around 2:15 p.m., he said in a phone interview Tuesday. Within minutes, he said, officers blocked off Heather Road and ordered residents to shelter in place. Police vehicles and emergency crews from neighboring towns and counties soon lined the street, surrounding the house and establishing a perimeter, he said.

From inside her home next door, Erica Titlow, 35, said she looked out a window and saw the man standing at the front door of the house, which has French doors with large glass panes. He was in his underwear, she said, with blood on his chest and stomach. Deleo said he also saw the man and that he was holding a butcher’s knife with blood on the blade.

“I had no idea what was happening,” Titlow said. “I thought maybe he was having some kind of mental breakdown and had hurt himself.”

After the man retreated from the doorway, police used a bullhorn to call out to him, Titlow said, urging him to come outside. He did not, and the standoff continued for several more hours.

Officers surrounded the house but were unable to enter, Titlow said. Shortly before a SWAT team forced its way through the front door Monday evening, officers went door to door, asking Deleo and Titlow if snipers could use their second-floor windows to provide cover to officers on the ground. Both agreed, they said.

Titlow said she spent more than an hour hiding in her basement with her 2-year-old daughter while snipers were positioned inside her home. “I didn’t want her to see any of it,” she said.

Even after officers entered the house, the man was not immediately removed, Deleo said. He watched as police deployed gas canisters inside the home and heard them detonate. Firefighters later connected a hose to a nearby hydrant and sprayed water into the house, according to both Deleo and Titlow.

Sometime after nightfall — the exact moment is difficult to recall, Titlow said — officers pulled the man from the house. He was restrained on a stretcher as authorities wheeled him away, she said.

By Tuesday morning, police were still at the scene, Titlow said, though the activity had slowed. “It’s a lot quieter now,” she said.

Staff writer Robert Moran contributed to this report.