U.S. satellite systems detected heat around a Russian passenger jet before it crashed in Egypt and killed all 224 people aboard, two U.S. officials said Tuesday.

One of the officials said they ruled out a missile striking the Metrojet Airbus A321-200 because neither a launch nor an engine burn had been detected. The infrared activity that was detected could mean many things, including a bomb or that an engine on the plane exploded because of a malfunction. Aviation analyst Paul Beaver said the heat picked up by the satellite "indicates that there was a catastrophic explosion or disintegration of the airplane," but doesn't reveal what caused it. "It doesn't tell us if it was a bomb ... or if somebody had a fight in the airplane with a gun there is a whole raft of things that could happen in this regard," he said.

He said it also could indicate a fuel tank or engine exploding, although "engines are designed so that if something malfunctions or breaks off it is contained within the engine." Both U.S. officials spoke on condition of anonymity because they weren't authorized to discuss the information publicly.

The joint investigation committee, which includes Egyptian and Russian experts as well as representatives from Ireland, where the plane was registered, will conclude its last field inspection at the crash site and start working on the black boxes, said Egyptian Civil Aviation Minister Hossam Kamal. Kamal says it "will take some time" to produce the final report and that the committee "has all the tools and experts to deal with the investigation."

Russian Transport Minister Maxim Sokolov said in televised remarks that Russian experts already had conducted a preliminary inspection of the two "black boxes" and had seen information from Egypt's flight control radars, but he wouldn't mention any further details.

The Metrojet flight was en route from Egypt's Red Sea resort of Sharm el-Sheikh to St. Petersburg when it crashed in the Sinai Peninsula after breaking up at high altitude, Russian aviation officials said. All of the victims, except for four Ukrainians and one Belarusian citizen, were Russian vacationers flying home.

Islamic State of Iraq and al-Sham (ISIS) militants insisted that they had "brought down" the Russian plane because of Moscow's recent military intervention in Syria against the extremist group. But the group did not provide any evidence to back up its claim, and militants in northern Sinai have not shot down any commercial airliners or fighter jets.

Alexei Smirnov of the Russian Emergency Situations Ministry said 140 bodies and more than 100 body parts were delivered to St. Petersburg on two government planes on Monday and Tuesday and that a third plane is expected to bring more remains later on Tuesday. Families on Tuesday identified the first 10 victims.