The Israel Defense Forces indicated yesterday that it might not have been responsible for the deaths of at least 54 Lebanese, including 37 children , when a building bombed in an Israeli air strike in the village of Qana collapsed yesterday - but was unable to offer an alternative explanation.

There is an unexplained gap of about seven hours between the one Israeli air strike that hit the Qana building housing the civilians, which took place around 1 A.M. Sunday, and the first report that the building had collapsed, said the chief of staff of the Israel Air Force, Brigadier General Amir Eshel. Speaking at a press conference at the Kirya military complex in Tel Aviv last night, Eshel said that of three Israeli air strikes on Qana early Sunday, only the first strike hit the building in which the civilians were staying. The other two hit areas at least 400 meters away.

"I can't say whether the house collapsed at 12 A.M. or at 8 A.M.," said Eshel. "According to foreign press reports, and this is one of the reports we are relying on, the house collapsed at 8 A.M. We do not have testimony regarding the time of the collapse. If the house collapsed at 12 A.M., it is difficult for me to believe that they waited eight hours to evacuate it."

Eshel and Major General Gadi Eisencott, who heads the Operations Directorate in the General Staff, said Hezbollah had set up headquarters in Qana and that militants fired about 150 Katyusha rockets at parts of northern Israel, including Haifa and the Galilee panhandle, from Qana. Some of the rockets, the army said, were fired from the built-up areas of the village.

In the second IAF strike on Qana, which took place at around 2:30 A.M. Sunday, IAF planes bombed two targets located about 500 meters from the building that collapsed, and in the third strike, at around 7:30 A.M., three targets were bombed 460 meters away from the building, Eshel said. He told reporters that an analysis of photographs of the strikes, taken by cameras installed in the warplanes, showed that the four bombs dropped during the second and third strikes hit the intended targets, and that an IAF plane sent on a photo sortie in the afternoon confirmed that the intended targets had been hit.

The IDF has not released the aerial photographs, which Eshel said were being processed.

Addressing the possibility that the building may have collapsed because the IAF bombing triggered a delayed explosion of weapons stored inside, Eshel said: "I don't want to get into conspiracy theories. We will work diligently and collect every detail, so as to understand what happened there. I hope that we will know in the end, but I'm not sure. It's possible that we will never know what exactly happened there."

The IDF screened a video yesterday showing rocket launches from Qana, and said it chose the objectives in the village by analyzing the locations from which Hezbollah had fired rockets on Israel. However, the house that was hit had no direct connection to the rocket-launching cells. Nonetheless, IAF officials said that immediately after firing rockets at Israel, some Hezbollah cells hide in civilian houses in built-up areas in southern Lebanon.

IDF Chief of Staff Dan Halutz and other senior officers expressed regret yesterday over the deaths of the civilians. They said the IDF was not aware that the civilians were in the village and had expected them to leave Qana the week before, following Israeli warnings of an impending attack.

Eisencott blamed Hezbollah for the deaths, saying the group uses the civilian population as a human shield.