The gunman, 41-year-old Jiverly Wong, had been taking classes at the American Civic Association, which helps immigrants assimilate, until last month, Police Chief Joseph Zikuski said.
The body armor indicates that "at one point in his thinking process that he was going to take the police on or at least try to stop us from stopping him," Zikuski said.
"He must have been a coward," Zikuski said, speculating that he decided to turn the gun on himself when he heard sirens.
"He had a lot of ammunition on him, so thank God before more lives were lost, he decided to do that," Zikuski said.
The police chief said Wong was depressed after recently losing a job and angry that he couldn't speak English well.
"He recently lost a job, spoke very little or no English, and was angry because people looked down upon him," Zikuski told Early Show anchor Erica Hill. "That's all we have at this point. There's been no notes or anything like that to indicate what his motives may have been and we're hoping to get some more light shed on why he did something as horrible as this. But that's all we may end up with."
Wong had a permit for the two handguns he used, Zikuski said. Most of the victims had multiple gunshot wounds, he said.
Wong, who used the alias Jiverly Voong, believed people close to him were making fun of him for his poor English language skills, Zikuski said.
It was at least the sixth fatal mass shooting in the U.S. in the past month, and the nation's deadliest since April 2007, when 32 people and a gunman died at Virginia Tech.
The shootings took place in a neighborhood of homes and small businesses in downtown Binghamton, a city of about 47,000 situated 140 miles northwest of New York City.
Wong was ethnically Chinese but from Vietnam, a friend said Saturday. He was angry about recently losing a job, could not find work, and complained that his unemployment benefit checks were only $200 a week, said Hue Huynh, a Binghamton grocery store proprietor whose husband worked with Wong years ago.
Wong had driven a truck in California before recently returning to Binghamton, only to lose a job there, Huynh said.
"He's upset he don't have a job here. He come back and want to work," she said. Her husband tried to cheer him by telling him he was still young and there was plenty of time to find work, but he complained about his "bad luck," she said.
"It Was Just Panic"
Shortly before 1030 a.m. Friday, Wong used his vehicle to block the back door of the American Civic Association building, before walking in the front door.
Wong used two handguns to kill a receptionist and shoot two others at the front desk. He then moved to the corner of the building, killing 11 more.
"It's crazy, it's kind of scary," said eyewitness Robert Wise. "Like, you see this in movies. You don't expect this to happen in Binghamton."
Wong then opened fire on a room full of immigrants taking a citizenship class.
Terrified people, their only escape route blocked, scrambled into a boiler room and a storage room and prayed he wouldn't follow.
"I heard the shots, every shot. I heard no screams, just silence, shooting," said Zhanar Tokhtabayeva, a 30-year-old Kazakh who was in an English class when her teacher screamed for everyone to go to the storage room. "I heard shooting, very long time, and I was thinking, when will this stop? I was thinking that my life was finished."
Another receptionist, 61-year-old Shirley DeLucia, played dead after she was shot in the abdomen and called the emergency dispatcher to get police to the scene within two minutes.
Zikuski said the injured receptionist stayed on the phone for 90 minutes, "feeding us information constantly," despite a serious wound in the abdomen.
"She's a hero in her own right," he said.
DeLucia was in critical condition at a hospital Saturday, along with another victim in the same condition and another in serious condition. A fourth victim was in stable condition at another hospital.
Thirty-seven others made it out, including 26 who hid for hours in a basement boiler room while police tried to determine whether the gunman was still alive and whether he was holding any hostages, Zikuski said.
Police heard no gunfire after they arrived but waited for about an hour before entering the building to make sure it was safe for officers. They then spent two hours searching the building.
They led a number of men out of the building in plastic handcuffs while they tried to sort out the victims from the killer or killers.
Most of the people brought out couldn't speak English, the chief said.
Alex Galkin, an immigrant from Uzbekistan, said he was taking English classes when he heard a shot and quickly went to the basement with about 20 other people.
"It was just panic," Galkin said.
Wong was found dead in an office with a self-inflicted gunshot wound, a satchel containing ammunition slung around his neck, authorities said. Police found two handguns - a 9 mm and a .45-caliber - and a hunting knife.
Jack Levin, director of the Brudnick Center on Violence at Northeastern University and an expert on mass murderers, told The Early Show that .
"He was going to take his life, but first he was going to get even," Levin said. "He was going to get sweet revenge against the other immigrants who had looked down upon him, among whom he had lost face. To him, that was an extremely important thing."
A woman who answered the phone at a listing for Henry D. Voong said she was Jiverly Voong's sister but would not give her name. She said her brother had been in the country for 28 years and had citizenship.
Friday evening investigators searched the home of the shooter, who lived only three-and-a-half miles away from the scene of his horrific crime.
"They are a very nice family, good family, educated family," said grocer Thanh Huynh. "You know, nice parents, nice sister, brother."
Accounts varied about the suspect's work history. Zikuski told NBC television's "Today" show that the shooter had worked in Binghamton for Shop-Vac, which closed in November. The sister told the AP on Friday that her brother worked at a company where "they make the vacuums."
Initial reports suggested Voong had recently been let go from IBM, which has roots in the region, but a person at IBM said there was no record of a Jiverly Voong ever working there. His father, Henry Voong, does work there as a contractor.
Huynh said her husband had worked with Voong years ago at IBM and that he had recently been let go from IBM again after returning from California.
The attack at the American Civic Association, which helps immigrants settle in this country, came just after 10 a.m. as people from all over the globe - Latin America, China, Kazakhstan, Vietnam, Africa - gathered for English and citizenship lessons in an effort to become a bigger part of their new home.
Wong parked his car against the back door before barging through the front and opening fire, apparently without saying a word. He then entered a room just off the reception area and fired on a citizenship class while terrified people scrambled into a boiler room and a storage room.
Abdelhak Ettouri, a Moroccan immigrant who lives in nearby Johnson City, told the Binghamton Press & Sun-Bulletin he found the back door locked when he tried to flee, then ran to hide in the basement as he heard 12 to 14 shots: "Tak-tak-tak-tak."
Hoi Nguyen of Binghamton said his 36-year-old daughter Phuong Nguyen, who survived the massacre, was taking an English class in the basement when the gunfire started.
"She said it sounded like a firecracker and everyone in the class was startled," he said. "Then the teacher locked the door, called the police, then told everyone they couldn't leave the room."
Police arrived in minutes, heard no gunfire and waited for about an hour before entering the building to make sure it was safe for officers. They then spent two hours searching the building. They led a number of men out in plastic handcuffs while trying to sort out victims from the killer or killers.
The Binghamton region was the home to Endicott-Johnson shoe company and the birthplace of IBM, which between them employed tens of thousands of workers before the shoe company closed a decade ago and IBM downsized in recent years.