It's still unclear why a 60-year-old man armed himself with a high-powered rifle and opened fire on his neighbors and armored police vehicles Sunday in rural Snohomish County before being shot himself.

A sniper who opened fire in the woods northeast of Arlington, wounding one man and peppering vehicles with gunfire, apparently acted alone, according to the Snohomish County Sheriff's Office.

The gunman, armed with a rifle equipped with a scope, shot a man in the leg around 1:30 p.m., sparking an hours-long standoff that ended when the suspect's body was found about 8 p.m.

Sheriff's deputies, as well as police from Everett, Lynnwood and Edmonds, launched a search for a possible accomplice, but it was called off around 11:30 p.m.

The Sheriff's Office on Monday was not yet ready to say definitively that deputies shot the man, but acknowledge that was the most likely scenario. Deputies fired on him around 4:30 p.m. during the incident, but the county medical examiner has not yet performed an autopsy.

"There were a lot of shots being fired at the time, so we don't want to rule out anything," said Shari Ireton, communications director for the Sheriff's Office. "We haven't confirmed that is the cause of death, and we don't know where that bullet came from at this point. It's very hard to determine exactly where that bullet came from because it was a tactical team."

Ireton said two deputies have been placed on administrative leave, standard procedure after an officer-involved shooting until an investigation is complete.

The man's name has not been released, but authorities said he was a 60-year-old Arlington resident.

Detectives returned to the area in the 17000 block of Jim Creek Road on Monday to process the scene and gather evidence, Ireton said, and remained there until about 5 p.m. Area residents, who were evacuated during the standoff, have been allowed to return home.

The incident began when a 26-year-old man walking near Jim Creek was hit in the calf by gunfire and then reported hearing multiple gunshots coming from the woods in the sparsely populated area. The man was taken to Cascade Hospital in Arlington, where he was treated and released.

Within 10 minutes, a sheriff's SWAT team arrived. Sheriff's spokesman Steve Dittoe said an armored vehicle brought in to use in the search for the man was hit by several rounds of gunfire.

The man also fired on vehicles in the area, the Sheriff's Office said.

Tabitha Spoiala reported a bullet went through a boat on a trailer.

"It went right in through there, on that side of the boat, and then it went through the cooler," she told KOMO-TV.

Residents who believe their vehicles were struck by bullets or who may have other information on the shooting are asked to call the sheriff's anonymous tip line at 425-388-3845.

Throughout much of the afternoon Sunday, authorities tried to determine where the shots were coming from and whether more than one person was doing the shooting. Civilian vehicles struck by gunfire were found with bullet holes on more than one side.

Dittoe said several area homes were evacuated, and people were urged to steer clear of Jim Creek Road between the 15000 and 25000 blocks. Even after the body of the suspected gunman was found, authorities repeatedly asked for police dogs to help explore the surrounding area.

Ireton said police found one weapon near the body of the dead suspect.

Seattle Times staff reporter Craig Welch and news researcher Miyoko Wolf contributed to this report.

Craig Welch: 206-464-2093 or cwelch@seattletimes.com. On Twitter @craigawelch.