Two Arab-Israeli men, Mohammed Zedan and Sheikh Hamad Abu Daabis, were on the flagship Mavi Marmara when it was seized as part of the May 31 operation to stop a six-ship flotilla which was trying to run Israel's Gaza blockade.
"I cannot tell you regarding who attacked first, who beat up whom first. I did not see it with my own eyes," Abu Daabis said.
Zedan said he was told by organisers of the trip that the 4,000-tonne ship carried food, medicines and toys for the Gaza population.
He was asked by members of the panel how he thought the massive passenger ferry could dock and offload its cargo at Gaza's tiny fishing harbour.
"Technical matters are not my business and I did not ask," he said. "The route of the ship, heading for Gaza, was a political message. It was a message that the people of Gaza are not alone."
When Abu Daabis was asked if he was aware that it was against the law for Israeli citizens to enter Gaza, he said he thought there was a high probability they would never reach their destination.
"I expected that the Israeli forces would intercept us in international waters and there would then have been some sort of international intervention which would have lasted for some days and a solution would have been found," he said.
"We thought that we would then have been allowed to go to a friendly country, Turkey for example."
Until Monday, the four-member panel had not heard any first-hand testimony from people who sailed on the Mavi Marmara, although it is urging more passengers to give evidence.
Israel says its soldiers fired in self-defence after they were attacked with clubs and knives, but activists say the Israelis opened fire as soon as they rappelled from helicopters on to the Mavi Marmara's upper deck.
The army has barred soldiers who took part in the raid from testifying before the commission.
Abu Daabis, a religious leader from southern Israel, said he was on an upper deck participating in pre-dawn Muslim prayers when he heard a stun grenade going off.
"We heard a very loud explosion which shook the ship, we didn't know where it was coming from," he said. "It was the stun grenade which stopped the prayer."
Noise and confusion followed and the ship's captain gave orders over the tannoy system for passengers to return below decks to the seating area, he said.
From there, the witnesses said, their view was limited to what they could see in the darkness though a small porthole.
"I heard helicopters overhead and heard shooting. I did not see what was going on," said Zedan.
The two witnesses were due to testify on October 13 but did not show up because they did not want to be seen as cooperating with what they saw as a biased inquiry.
They were compelled to appear on Monday after being subpoenaed.
The Tirkel commission, which the Israeli government set up in June, has a mandate to look into the legality of the raid in which nine Turkish activists were shot dead.
It has asked the ship's Turkish captain and other Turkish nationals who were on board the vessel to testify but so far no one has responded.
It has invited anybody willing to testify to contact panel spokesman Ofer Lefler via the website http://www.turkel-committee.gov.il/index-eng.html.
The deadly raid sparked international outrage and led Israel to ease a four-year blockade of Gaza to allow in all purely civilian goods as well as construction materials for internationally supervised projects.
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