Fourteen civilians died after being shot on Bloody Sunday
The inquiry is investigating the circumstances surrounding the deaths of 13 civilians shot dead by British paratroopers during a civil rights march in Londonderry on 30 January 1972.
Another man died later from his injuries.
The then Bernadette Devlin was a young republican activist who narrowly escaped the gunfire, according to evidence already heard by the tribunal.
Several witnesses have described seeing bullets hitting the wall behind her as she stood on a platform and addressed the crowd assembled at Free Derry Corner in the city's Bogside district.
There was speculation Mrs McAliskey might not go into the witness box after it emerged that lawyers for the soldiers had asked the tribunal to get intelligence material on civilian witnesses.
Intelligence files
Earlier on Tuesday, Tribunal Chairman Lord Saville said witnesses concerned about the matter did not have to give their evidence until he decides whether or not to make use of intelligence files.
Lord Saville of Newdigate said there was no question of "springing" intelligence material on witnesses called to give evidence at the hearing.
Mrs McAliskey has said in written statements that she did not know Martin McGuinness, then the IRA's number two in Derry.
She told Christopher Clarke, QC, Counsel to the Inquiry, she had no knowledge of any arrangements made with the IRA to stay away from the demonstration.
Mrs McAliskey said: "I had no reason to consider the matter or ask the question 'Where will the IRA be?' or 'Where will the IRA's weapons be while we are marching?"'
Mrs McAliskey described three waves of shooting, the first two from the city walls overlooking the Bogside to the east before a third burst of gunfire came from the south, from where paratroopers moved into the area.
She said that after the first shots "somebody in front of me says that they are shooting at me".
She said there was nowhere for the 30,000 people to run.
'Get off the streets!'
"One moment I was looking at faces looking up at me, the next moment I was looking at the crowns of people's heads. I was telling them to stay down, to get off the streets," she said,
At times she broke off during her testimony when reliving events.
She said: "I think it maybe registers that there is nobody here, only me, dead people and the British Army coming down in front of me towards me.
"The only clear memory I have - which I have now as I speak of it - is terror. That is all I remember, sheer terror.
"I was looking at something and yet it was happening in front of my eyes in slow motion. I could not hear myself saying two different things, and I do not know which of them I was saying out loud.
"I may well have been thinking that people should not run, and I may well have been saying out loud the ritual prayers for the dying or I may have been doing it the other way round."
The Bloody Sunday inquiry was established in 1998, is chaired by Lord Saville of Newdigate and is expected to run for another two years.