MOSCOW, August 17 (RIA Novosti) - Two men and a woman who suffered severe burns following a fire caused by the collision of two Su-27 fighters near Moscow remain in a hospital in serious condition, a doctor said on Monday.

A total of five civilians were hospitalized after burning debris from the two planes fell on a small community near Zhukovsky airfield, east of Moscow, destroying three houses and a car.

"A woman, her husband and their neighbor are in an intensive care unit. Their condition is still very serious," the source in a Moscow clinic said, adding that two other civilians were in mildly serious condition.

Two Su-27 Flanker jet fighters from Russia's elite aerobatics group Russkiye Vityazi (Russian Knights) collided on Sunday in mid air during a rehearsal for the MAKS-2009 air show near Moscow.

All three pilots ejected, and two of them were later found on the ground in serious but satisfactory condition. The dead pilot, whose parachute reportedly caught fire in the air, was identified as Col. Igor Tkachenko, 45, commander of the Russian Knights.

According to preliminary investigations, the accident was most likely caused by pilot error during an aerobatics maneuver, although the possibility of a technical failure has not been ruled out.

On-board recording devices have been found at the scene of the accident, and the investigators continue to recover the main parts of the aircraft for further analysis.

One of the two surviving pilots has been hospitalized with a spinal fracture, police said. No information is so far available on the condition of the third pilot.

The organizer of the MAKS-2009 air show said on Sunday the tragedy would not delay the show, scheduled to start on Tuesday.

Meanwhile, the Russian Interior Ministry has pledged to ensure security and safety during the most important air show in Russia.

"We have taken extra security measures and we are ready for the show," Deputy Interior Minister Nikolai Ovchinnikov said, adding that over 3,500 police, 1,200 interior troops and personnel from various security-related agencies will be deployed at the MAKS-2009.