HERKIMER, N.Y. — A man neighbors called a loner coolly walked into an upstate barbershop, asked the owner if he remembered him and then abruptly opened fire with a shotgun, killing two men in the opening salvo of a rampage that left four dead, two wounded and a heavily armed police force bunkered down around an abandoned building, police and family members said.

Police officers were fired on from the building, which used to house a bar, on Wednesday afternoon while looking for 64-year-old Kurt Myers, state police Superintendent Joseph D’Amico said. At least one officer returned fire, and later it was unknown if Myers was still alive, D’Amico said.

“We’re in no rush to bring this to a conclusion,” D’Amico said, adding that the main objective was to make sure no one else was hurt.

Early Thursday, two loud booms were heard outside the building in downtown Herkimer, and police periodically blared sirens in an apparent attempt to encourage Myers to surrender, if alive. A police robot has been at the scene since Wednesday, and a witness said it went into the building early Thursday and came back out again.

Police spokesman Jack Keller said the troopers and local police would watch the building all night under the assumption that Myers was still alive.

Police said Myers’ rampage started with a fire in his apartment in the nearby village of Mohawk at about 9:30 a.m. Wednesday. D’Amico said Myers then drove to John’s Barber Shop around the corner and used a shotgun to kill two customers, whom he identified as Harry Montgomery, 68, and Michael Ransear, 57, a retired corrections officer. The shop’s owner, John Seymour, and another customer, Dan Haslauer, were listed in critical condition at a Utica hospital.

D’Amico said the gunman then drove to Gaffy’s Fast Lube in nearby Herkimer and used the shotgun to kill Thomas Stefka, an employee, and Michael Renshaw, a customer who was a 23-year veteran of the state Department of Corrections.

John Seymour told his sister, Mary Hornett, the barbershop attack came out of nowhere.

“He just said that the guys were in the barbershop and this guy comes in and he says, ‘Hi John, do you remember me?’ and my brother said, ‘Yes, Kurt, how are you?’ and then he just started shooting,” Hornett said.

Hornett said her brother, who was hospitalized in critical condition, was doing well after being shot in the left hand and right hip.

“My brother couldn’t think of any reason why he would do such a thing,” she said of Myers, a former customer who hadn’t been in the shop for a couple of years.

Gov. Andrew Cuomo, in a press conference in Herkimer, called it “truly an inexplicable situation.”

“There’s no apparent motive to the best of our knowledge at this time to provoke these attacks,” he said.

D’Amico said police had not had any communication with Myers, whose only known police record was a 1973 drunken-driving arrest.

Police positioned in front of a block of small businesses topped with apartments in the village of Herkimer were still looking for Myers on Wednesday evening.

Late into the night, neighbors grew frustrated with the long standoff. Pat Roberts stood shivering on the corner, waiting to get back to his wife and 4-year-old son, who remained trapped in their apartment in the lockdown zone.