WATERTOWN, Mass. — Doug Murphy, living near the center of the search zone in Watertown grappled with the idea that the bombing suspect might try to storm his home or already could be hiding inside it.

Murphy, 33, who grew up in the Androscoggin County town of Poland, and his wife, Zoey Murphy, 33, who grew up in Auburn, woke up about 5 a.m. Friday to what they thought was a normal day.

When he looked out the window, instead of the usual early morning traffic, he saw that the corner of Walnut and Lincoln streets had become a center of law enforcement activity, with 25 to 50 armed SWAT team members exiting a large, armored truck.

“Especially, at first, for the first half hour, it was pretty frightening,” Murphy said. “We didn’t know where we should be. Should we go to the basement? Should we not be near the windows?”

Murphy, whose mother, Christine Whitmore, lives in Benton, said he was concerned that the bombing suspect could be hiding in his home. He began looking for signs of forced entry and searching rooms to see whether he unknowingly was harboring a killer.

For the Murphys in Watertown, the corner outside had activity throughout the early morning hours, with an FBI command officer whom he recognized from television coverage of the search spending a good portion of the morning there. Eventually, SWAT team members went door to door, searching homes.

A group of three knocked on his door and asked whether everyone was OK, he said. Murphy declined their offer to search his home, he said, because “I told them I checked everything.”

The SWAT team members asked whether their doors and windows were locked, then went upstairs to search a neighbor’s home, guns held ready.

A little later, Murphy said he looked out his window, and a SWAT team member in the yard motioned him away from the window.

As the activity slowed, the Murphys made coffee and ate yogurt while watching news on TV.

In the late morning Friday, Murphy said there was less activity outside, but he remained cautious.

“I can see an officer walking up my street right now holding what looks like an AK-47 (assault rifle) in both hands,” he said. “We’re not out of the woods yet.”