Irish Poet James Stephens wrote and published an eye witness account of the Easter 1916 Rebellion titled The Insurrection in Dublin (1916).
The following excerpts are from that account.

MONDAY

At the corner of Merrion Row I found the same silent groups, who were still looking in the direction of the Green, and addressing each other occasionally with the detached confidence of strangers.  Suddenly, and on the spur of the moment, I addressed one of these silent gazers.
        "Has there been an accident?" said I.
        I indicated the people standing about.
        "What's all this for?"
        He was a sleepy, rough-looking man about forty years of age, with a blunt red moustache, and the distant eyes which one sees in sailors.  He looked at me, stared at me as at a person from a different country.  He grew wakeful and vivid.
        "Don't you know?" said he.
        "And then he saw that I did not know.
        "The Sinn Feiners have seized the city this morning."
        "Oh!" said I.
        He continued with the savage earnestness of one who has amazement in his mouth:
        "They seized the city at eleven o'clock this morning.  The Green there is full of them.  They have captured the Castle.  They have taken the Post Office."
        "My God!" said I, staring at him, and instantly I turned and went running towards the Green.

WEDNESDAY

It was three o’clock before I got to sleep last night, and during the hours machine guns and rifle firing had been continuous. This morning the sun is shining brilliantly, and the movement in the streets possesses more of animation than it has done. The movement ends always in a knot of people, and folk go from group to group vainly seeking information, and quite content if the rumour they presently gather differs even a little from the one they have just communicated. The first statement I heard was that the Green had been taken by the military; the second that it had been re-taken; the third that it had not been taken at all. The facts at last emerged that the Green had not been occupied by the soldiers, but that the Volunteers had retreated from it into a house which commanded it. This was found to be the College of Surgeons, and from the windows and roof of this College they were sniping. A machine gun was mounted on the roof; other machine guns, however opposed them from the roofs of the Shelbourne Hotel, the United Service Club, and the Alexandra Club. Thus a triangular duel opened between these positions across the trees of the Park. Through the railings of the Green some rifles and Bandoliers could be seen lying on the ground, as also the deserted trenches and snipers’ holes. Small boys bolted in to see these sights and bolted out again with bullets quickening their feet. Small boys do not believe that people will really kill them, but small boys were killed.