According to various reports, the house the Shia were meeting in, in Giza, Cairo, was attacked and burned. Al Badil News quotes a witness from the mortuary [ar] who says  that one of those killed was slaughtered and the remaining three had injuries to their heads. The horrific incident unleashed anger online.
Hazem Barakat documented the crime, sharing bloodied photographs and a video of the attack (Warning: Graphic video ) online. On Twitter, he says he was threatened  for sharing the incident he has witnessed. He adds [ar]:
انا على اتم الاستعداد للشهاده امام النيابه وهقول كل اللى حصل بالتفاصيل وهقول على الشيوخ اللى حرضت على القتل
@7azem122 : I am ready to testify at the Public Prosecutor and I will say what happened in detail and I will say that the clergymen were the ones who instigated this crime
التحريض على الشيعه بدأ من اسبوعين فى جميع المساجد والنهارده كان التنفيذ شيوخ ولاد دين كلب ” قتلوهم وعندهم اطفال لسه صغيرين :(
@7azem122:  Instigating against the Shia started two weeks ago in all the mosques and today they executed their plan. Those clergymen are sons of dogs. They killed people with young children
Five hours ago he tweeted:
السلفيين بدأو يكسرو سقف البيت اللى فيه الشيعه مشهد سيريالى رهيب
@7azem122: The Salafists have started to break the roof of the house the Shia are in. It is a surreal scene.
He also claims the police, including officers, were standing by and watching as the lynching took place.
The incident was met with anger online.
Satirist Dr Bassem Youssef tweets:
النهاردة شيعي بكرة صوفي بعده قبطي قبله بهائي و بعدين مسلم مش موافق على تطبيق الشريعة بفكركم و بعدين واحد شكله مش عاجبك.
@DrBassemYoussef : Today it is a Shia; tomorrow a Sufi, and then a Copt, a before him a Bahai. Afterwards it will be a Muslim who doesn't agree with the way you want to implement Sharia (Islamic teachings) with your ideology and then it will be someone whose look you don't like
Egyptian blogger Zeinobia shares a similar thought:
و النهاردة الشيعة و بكرة جارك اللى مش متفق معاك سياسيا و فكريا
@Zeinobia:  And today it is the Shia and tomorrow your neighbour who is not in agreement with you politically and intellectually
Ahmed Abou Hussein asks:
لما شيخك يكفر المتظاهرين ويلقب الشيعة بالأنجاس ماتستغربش انهم يقتلوا. يا مرسي السؤال مش انت فقدت شرعيتك ولا لأ، السؤال انت فقدتها كام مرة؟
@abouhussein7:  When your clergyman [President Mohamed Morsi] says that the protestors are infidels and that the Shia are unchaste, don't be surprised when they are killed. Morsi, the question is not whether you have lost your legitimacy. The question is: how many times have you lost your legitimacy?
Ahmad Khalil is surprised at the way people are reasoning murder:
السلفيين قتلوا ٤ شيعة ، الغريب فى الامر ان من يستنكر هذا الفعل يقول دم المسلم حرام يعنى دم المسيحى حلال ، الافكار الطائفية اصابت الجميع
@ahmad_khalil: The Salafists have killed four Shia. What is surprising is that there are some among those who are condemning the act who say that spilling the blood of a Muslim is Haram [forbidden in Islam]. It is as if spilling the blood of a Christian is Halal (acceptable in Islam]. Such sectarian ideas have inflicted everyone.
Sherif Azer notes [ar]:
فيه احداث و تصريحات كتير حصلت في الفترة الاخيرة كانت بتمهد للهجوم على #الشيعة في مصر.عدم الاستعداد لموقف زي ده في حد ذاته جريمة #مصر
@sherif_azer : There were a lot of incidents and statements that have happened over the past period which prepared the scene for the attack on the Shia in Egypt. Not being prepared for such an incident is a crime in its own
And Adel Salib wonders why people are shocked that the Shia are being attacked in Egypt when the police previously attacked – and killed – Egyptian Copts:
مندهش من المندهشين ان الشرطة وقفت تتفرج علي قتل الشيعة ؛ اذا كان الشرطة كانت من شهرين بتضرب الكتدرائية انتم عالم مغيبين ولا بتستهبلوا ؟
@Adel_Salib : Someone is surprised that the police were watching while the Shia were being murdered when two months ago the police were attacking the Cathedral. Are you under a spell or just stupid?
زعلان ان المسلمين السنة بيتدبحوا في بورما ..وفرحان ان المسلمين الشيعة بيتحرقوا أحياء و يتمثل بجثثهم .. انت لازم تقوم تشوف دكتور بيطري كويس
@ali4592000 : Are you angry that Sunni Muslims are being killed in Burma and happy that Shia Muslims are being burnt alive in Egypt and their corpses defiled? You should see a good veterinarian
Rawah Badrawi shares some history:
@RawahBadrawi : Cairo was founded by Shias you Neanderthals. They established half its heritage sites including Al Azhar.
And Yemeni blogger Noon Arabia concludes:
نحن نعود إلى زمن الجاهليه. الإسلام بريء مما يحدث الآن من سفك الدماء. #مصر #لبنان #سوريا
Of course not everyone was horrified by the attack. Blogger Mohamed Beshir shares a tweet by a presenter at the Egyptian Television named Mohammed Saber, who is celebrating the murder of the Shia and calling for more deaths.
دة مذيع ف التلفزيون المصري سعيد بقتل الشيعة والناس بترد عليه يأكد ويبشرهم
@Gemyhood : This is a presenter at the Egyptian [state] television happy at the murder of Shia