(CNN)President Barack Obama on Sunday night will deliver a rare Oval Office address about terror threats in the aftermath of the San Bernardino, California, shootings that claimed 14 lives. CNN and other networks will broadcast it live at 8 p.m. ET.

The White House says the president will provide an update on the investigation. Federal authorities have said the attacks are being investigated as an act of terrorism.

"The President will also discuss the broader threat of terrorism, including the nature of the threat, how it has evolved, and how we will defeat it," White House Press Secretary Josh Earnest said in a statement. "He will reiterate his firm conviction that ISIL will be destroyed and that the United States must draw upon our values -- our unwavering commitment to justice, equality and freedom -- to prevail over terrorist groups that use violence to advance a destructive ideology."

ISIL on Saturday hailed the San Bernardino shooters as "supporters" of the terror group -- a message that came after U.S. investigators said they suspect one of the shooters professed loyalty to the Islamist network, CNN reports.

Republicans, on the presidential campaign trail and in Congress, have in recent days lambasted President Obama over his response to the San Bernardino killings. They've been particularly withering about comments by the president supporting gun control measures. In his Saturday radio address Obama said it's "insane" that people on the "no-fly" list are permitted to buy guns.

Sunday's Oval Office address will be only the third of Obama's presidency. The prior two occurred in 2010, about the end of U.S. operations in Iraq, and the Gulf oil spill. He has delivered other prime time speeches from the White House, focusing on the killing of Osama bin Laden, military intervention in Syria, immigration and other issues.