Police are piecing together why a jobless US immigrant killed 13 people and himself in the New York centre where he had been taught English.
The gunman at the heart of the tragedy in the quiet, small New York town of Binghamton has been identified as Jiverly Wong, reportedly of Vietnamese origin.
Wong blocked the back doors of the American Civic Association with his car and then burst into the front of the centre in a hail of gunfire.
He took dozens hostage in the four-hour spree and killed 13 people, before turning the gun on himself.
Police found two handguns and a satchel of ammunition.
Binghamton Police Chief Joseph Zikuski said no motive for the shooting had been determined, but he confirmed reports that Wong, who also went by the name Voong, had felt degraded by his inability to speak English and by a recent job loss.
"From the people close to him ... this action he took was not a surprise to them," Mr Zikuski told a news conference.
"He felt degraded from his inability to speak English and he was upset about that," he added.
Police say he had a permit for the two hand guns he used and he was wearing body armour.
Earlier, Pakistani Taleban leader Baitullah Mehsud called media organisations to claim responsibility for the attack.
But FBI spokesman Richard Kolko said that based on the evidence the militant's claim could be "firmly discounted".
Meanwhile, the governor of New York David Paterson has promised to help all those affected by the shooting rampage.
He has described the shootings as an outrage and he's promised to help.
Thirteen killed in shooting
On Friday morning, Wong barricaded the back door of the building with a car and, wearing body armor, entered the front and opened fire on two receptionists, killing one.
He then went to a classroom and fired, killing another 12 people who were taking English language instruction before killing himself.
Survivors said Wong did not speak before opening fire.
The four wounded, including a receptionist who called police, were expected to survive.
Police were alerted by an emergency call made by the first person shot by the gunman, a receptionist who was shot in the stomach, who pretended she was dead until she was able to escape.
Some people escaped to a basement and more than a dozen hid in a closet.