The gunman who killed 13 people at a community centre in Binghamton, N.Y., before taking his own life had complained about his poor English language skills and being jobless, friends and officials said Saturday.
Police Chief Joseph Zikuski said the gunman's name was Jiverly Wong, but he used the name Jiverly Voong as an alias.
He was a 42-year-old Vietnamese immigrant who had been taking classes at the American Civic Association building, where on Friday morning he killed a receptionist, then 12 people who were taking a citizenship class.
Wong was found dead in an office with a self-inflicted gunshot wound, authorities said. Police found two handguns — a 9-mm and a .45-calibre — and a hunting knife.
Zikuski said the man had a permit for the two guns and wore body armour, indicating he was prepared for a confrontation with police.
Wong had driven his car to the back door of the centre, using the vehicle to block the door.
One of the two receptionists, 61-year-old Shirley DeLucia, survived a gunshot wound to the abdomen and called police. She and three other victims remain in hospital.
Thirty-seven people made it out of the centre, 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.
Matthew Ryan, the mayor of Binghamton, told CNN that Wong felt people looked down on him for his poor language skills and his unemployed status.
Hue Huynh, a Binghamton grocery store proprietor whose husband worked with Wong years ago, said the man had complained about his "bad luck." He said he was also unhappy that his unemployment cheques were only $200 a week.
Investigators said they had yet to establish a motive for the shooting. It was at least the fifth fatal mass shooting in the U.S. in the past month, and the country's deadliest since April 2007, when 32 people and a gunman died at Virginia Tech.