A heavily armed man invaded a Newtown, Conn., elementary school today, killing his mother and 26 others, mostly children, federal and state sources tell ABC News.

The gunman, identified as Ryan Lanza, 24, of New Jersey, was killed inside of the school.

In addition to the casualties at the school, a dead body was also found in his home, officials said. Sources said Lanza was armed with four weapons and wearing a bullet-proof vest when he opened fire in the elementary school.

Among the dead was the gunman’s mother, found in the school, sources told ABC News.

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