President Barack Obama spoke to Connecticut's governor Friday and expressed condolences to those who lost loved ones in the elementary school shooting, the White House said.
Officials with knowledge of the incident said 27 people, including 18 children, were killed.
"As a father, incidents like these weigh heavily on him," White House spokesman Jay Carney said.
Obama was briefed on the shooting Friday morning by his counterterrorism adviser John Brennan and will continue to receive regular updates throughout the day. Carney said the president was likely to address the shooting later Friday.
In addition to his phone call with Connecticut Gov. Dan Malloy, Obama also spoke Friday with FBI director Robert Mueller. The FBI is supporting state and local law enforcement officials in Connecticut as they respond to and investigate the incident.
Carney said the administration would "do everything we can to support state and local law enforcement."
Asked whether the shooting would make gun control a higher priority on the president's agenda, Carney would say only that there would be a day for discussion on that policy issue.
"But I don't think today is that day," he said.