President Obama on Saturday refused to call Wednesday's shooting in San Bernardino an act of terrorism, even though the FBI says it now sees several signs that it was a terrorist attack.

Obama did, however, say again that it's "possible" it was terrorism.

"It is entirely possible that these two attackers were radicalized to commit this act of terror," he said in his weekly address. "And if so, it would underscore a threat we've been focused on for years — the danger of people succumbing to violent extremist ideologies."

The White House released a transcript of Obama's message at around 6 p.m. Friday, about four hours after the FBI announced that it was investigating the shooting as a terrorist event. The FBI said the "extensive planning" undertaken by Syed Rizwan Farook and his wife was one reason why the investigation was shifting toward looking for terrorism elements.

"There's a number of pieces of evidence that has essentially pushed us off the cliff to say we are now investigating this as an act of terrorism," said David Bowdich, the assistant director of the FBI's Los Angeles office.

Numerous reports have also noted that Farook's wife, Tashfeen Malik, pledged allegiance to the Islamic State before the attack began. However, the FBI has yet to confirm that the act was either inspired or orchestrated by the terrorist group.

While Obama gave a nod to the possibility of terrorism, he mostly focused his weekend address on the need for tighter gun control measures to prevent more shootings, a prescription Republicans continue to oppose.

"For example, right now, people on the No-Fly list can walk into a store and buy a gun," Obama said. "That is insane. If you're too dangerous to board a plane, you're too dangerous, by definition, to buy a gun. And so I'm calling on Congress to close this loophole, now."

Republicans have rejected the idea of banning guns for people on the terrorism watch list because that list is put together without any due process by federal officials, and has been known to contain errors. Republicans say it shouldn't be that easy for the government to take away people's rights under the Second Amendment to the Constitution.

Still, Obama said the proposal is the best way to make it a little bit harder for bad actors to get their hands on guns.

"We may not be able to prevent every tragedy, but at a bare minimum, we shouldn't be making it so easy for potential terrorists or criminals to get their hands on a gun that they could use against Americans," he said.