WASHINGTON — U.S. officials say they are growing increasingly convinced that the crash of a Russian aircraft in Egypt was the result of a bomb, as investigators collect evidence from what one lawmaker called “a 9/11” event for Russia.

Signs point to a bomb planted by a supporter of the Islamic State as the cause of the crash Oct. 31, Rep. Michael McCaul, R-Texas, chairman of the House Homeland Security Committee, said Sunday. McCaul was one of several senior lawmakers on committees related to national security who made that case Sunday.

Evidence collected from the aircraft’s “black box” data recorder, as well as information from satellite surveillance of the region, showed a burst of heat just before the plane lost altitude, he said.

“All indicators are pointing to the fact that it was ISIS putting a bomb on an airplane,” McCaul said on “Fox News Sunday.”

“I have a high degree of confidence. It’s been my gut (feeling) all along,” McCaul said. For Russia, “this is comparable to 9/11,” he said. The crash of the Russian airliner killed all 224 aboard.

The Islamic State, also known as ISIS, has threatened retaliation against Russia since Moscow began bombing militias in Syria fighting the government of Syrian President Bashar Assad, an ally of Russia.

Over the weekend, an Egyptian official confirmed that the plane’s cabin recorder captured a strange noise before the jet plunged from the skies. French sources familiar with the investigation described the sound on the cabin recorder as a violent and sudden explosion, echoing earlier speculation by British intelligence sources.

Despite growing speculation that a bomb may have exploded on the flight, though, the Egyptian head of the panel investigating the crash said Saturday it was too early to say for certain. Egypt risks losing vitally important tourist revenue if security concerns stop people from flying to its Red Sea resort at Sharm el-Sheikh. Russians and Britons make up a large share of the tourist traffic.

Reps. Peter T. King, R-N.Y., and Adam B. Schiff, D-Calif., said in a joint interview on ABC’s “This Week” that they are close to reaching the conclusion that a bomb caused the crash, as well as the need for more security precautions at airports in the region.

Schiff, the senior Democrat on the House Intelligence Committee, said the Islamic State “may have concluded that the best way to defeat airport defenses is not to go through them but to go around them with the help of somebody on the inside.”

If that’s the case, he said, “I think there are probably at least a dozen airports in the region and beyond that are vulnerable to the same kind of approach, which is exactly why we have to harden those defenses.”

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