What information do we have about the Deir Yassine Massacre that happened in Palestine Does it qualify as a genocide ?

The following survivor accounts of Deir Yassin appeared in the Dossier 179/110/17/GS and were labeled "Secret" and were the result of an investigation about 4 days after the capture of the village. They were not made generally available for 25 years so it is difficult to assume it was made for anti-Irgun propaganda purposes at the time. If anything keeping it secret indicates the British protecting the reputation of the Irgun.
Journalists Larry Collins (UPI/Newsweek) and Dominique Lapierre (Paris-Match) reviewed the contents of the reports for their bestseller O Jerusalem! (1972). They noted that the dossier "contain[ed] the interrogation reports of the massacre's survivors by a team of British police officers together with corroborating physical evidence obtained through medical examination of the survivors by a doctor and nurse from Government Hospital in Jerusalem."
Direct statements of survivors will follow. In any event, CID Deputy Inspector General Catling concluded:

"The recording of statements is hampered also by the hysterical state of the women who often break down many times whilst the statement is being recorded. There is, however, no doubt that many sexual atrocities were committed by the attacking Jews. Many young schoolgirls were raped and later slaughtered. Old women were also molested. One story is current concerning a case in which a young girl was literally torn in two. Many infants were also butchered and killed. I also saw one old woman . . . who had been severely beaten about the head with rifle butts. Women had bracelets torn from their arms and rings from their fingers and parts of some of the women's ears were severed in order to remove earrings."

Survivor statements from the reports are below. Collins and Lapierre refused to use later Arab sources of atrocities so as to avoid the risk of "any Arab tendency to magnify the events in retrospect." In conducting their own journalistic investigation, however, the authors met with survivors and noted that "their accounts in 1969 amply confirmed the details of the [secret] British report."
SURVIVOR RECOLLECTIONS FROM DEIR YASSIN:
Mr. Fahimi Zeidan, 12:

"The Jews ordered all our family to line up against the wall and they started shooting us. I was hit in the side, but most of us children were saved because we hid behind our parents. The bullets hit my sister Kadri [four] in the head, my sister Sameh [eight] in the cheek, my brother Mohammed [seven] in the chest. But all the others with us against the wall were killed: my father, my mother, my grandfather and grandmother, my uncles and aunts and some of their children."

Ms. Haleema Eid, 30:

"A man [shot] a bullet into the neck of my sister Salhiyeh who was nine months pregnant. Then he cut her stomach open with a butcher's knife."

Ms. Naaneh Khalil, 16, saw a man:

"take a kind of sword and slash my neighbor Jamil Hish from head to toe then do the same thing on the steps to my house to my cousin Fathi."

Ms. Safiyeh Attiyah, 41:

"I screamed but around me other women were being raped too. Some of the men were so anxious to get our earrings they ripped our ears to pull them off faster."

Mr. Mohamed Jaber, student:

"The Jews [broke] in, [drove] everybody outside, put them against the wall and shot them. One of the women was carrying a three month old baby."

Survivors' testimonies:
Eyewitness testimonies of the Deir Yassin massacre as told to journalist Elias Zananiri, previously published in 9.4.1997 in "Gulf News". On the eve of April 9th 1948, armed members of Jewish underground groups attacked the village, a strategic site towering Jerusalem from the West. After the fall of Al Qastal a few days earlier and the killing of Palestinian guerrilla leader Abdul Qader Al Husseini, Deir Yassin became the most important point on the road to Jerusalem.
Um Mahmud, wife of Abu Mahmud, was 15 years old at the time:

"We were inside the house. We heard shooting outside. My mother woke us up. We knew the Jews had attacked us. My cousin and his sister came running and said the Jews were already in our garden. In the meantime, fighting became heavier and we heard lots of gunshots outside. A bomb was thrown at us and it exploded close to where we were in the yard. (...) My sister- in-law did not want to leave. She was frightened. The girl was two months old and the boy about three. I took the two and my mother said we should go to my uncle’s house. I saw how Hilweh Zeidan was killed, along with her husband, her son, her brother and Khumayyes. Hilweh Zeidan went out to collect the body of her husband. They shot her and she fell over his body (...). I also saw Hayat Bilbeissi, a nurse from Jerusalem serving in the village, as she was shot before the house door of Musa Hassan. The daughter of Abu El Abed was shot dead as she held her niece, a baby. The baby was shot too (...). Whoever tried to run away was shot dead."

A.Y.J., Abu Yousef, also 70 years old. He lives in Amari refugee camp near Ramallah:

"(...) After the battle, the Jews took elderly men and women and youths, including 4 of my cousins and a nephew. They took them all. Women, who had on them gold and money, were stripped of their gold. After the Jews removed their dead and wounded, they took the men to the quarry and sprayed them all with bullets. (...) One woman had her son taken some 40 to 60 meters away from where she and the rest of the women stood by, and shot him dead. Then they brought Jewish kids to throw stones at his body. They later poured kerosene on his body and set it ablaze while the women watched from a distance. We later collected ourselves, & checked who was missing. At Jaffa Gate in Jerusalem, we were gathered by the Arab Supreme Committee. Each of us was looking for a son, a daughter, a sister or a mother. All men were busy fighting. Eyewitnesses were only women. The elderly men were told to remove the dead, both Arabs and Jews. They took the bodies of the Jews and left the Arab bodies until they later were thrown in a well in the village center."

Perhaps one of the most graphic witness testimonials comes from Othman Akel:

“I saw the Zionist terrorist soldiers ordering the bakery man of the village to throw his son in the oven and burn him alive. The son is holding the clothes of his father tightly and crying from fear and pleading to his father not to do it. The father refuses and then the soldiers hit him in his gut so hard it caused him to fall on the floor. Other soldiers held his son, Abdel Rauf, and threw him in the oven and told his father to toast him well-done meat. Other soldiers took the baker himself , Hussain al-Shareef, and threw him, too, in the oven, telling him, “follow your son, he needs you there”.

Other stories include tying a villager to a tree before burning him, rape and disembowelment. Dead villagers were thrown into pits by the dozen. Many were decapitated or mutilated. Houses were looted and destroyed. A number of prisoners were taken, put in cuffs, and paraded around West Jerusalem as war trophies, before being executed and dumped in the village quarry.
Further reading: Deir Yassin massacre in Palestine.