Police in Florida say a 19-year-old has confessed to shooting dead 17 people at a school on Wednesday.
Nikolas Cruz bought the assault rifle from a local gun store - passing a background check within minutes.
His lawyer has called him a "broken human being" and says he's 'sad', 'mournful' and 'remorseful', following the mass-shooting on Wednesday.
Police say he went to McDonald's and Subway after the shooting spree.
TV host Jimmy Kimmell is among those criticising Donald Trump over his response, which hasn't mentioned the country's gun laws.
A vigil's been held for the victims of America's third most-deadly school shooting.
Around a thousand people stood silently in Parkland, Florida.
Some carried candles - others held up signs demanding stricter gun controls.
Questions are now being asked about what the FBI knew about the 19-year-old suspect after they admitted receiving a warning about a social media post made by the Cruz last year.
Special agent Robert Lasky says it had a tip-off about an online comment he made.
