Who martyred imam Hussain A.S? Was it Shia or Sunni and sahaba?
Where were sunni and sahaba in karbala
Dr. Mustafa al-Shibi in al-Shiʿa wa Makanatuha fi al-Tashriʿ al-Islami
Al-Shibi states that al-ʿIjli placed the number of Companions who settled in Kufa alone at 1,500 Companions, apart from those who settled in the other regions of Iraq.
وأبلغ العجلي عدد الصحابة الذين سكنوا الكوفة فقط إلى ألف وخمسمائة صحابي، فضلاً عن باقي بلدان العراق.

Ziyad used to kill many shia in kufa
Al-Haythami in Majmaʿ al-Zawaʾid wa Manbaʿ al-Fawaʾid, V6 p295, Hadith 10604
Al-Hasan al-Basri said: “Ziyad used to pursue the Shia of Ali and kill them.” When this reached Imam Hasan ibn Ali (a.s.), he said: “O Allah, single him out through his death, for killing is an expiation.”
Al-Haythami states: “Al-Tabarani narrated it, and its narrators are the narrators of the Sahih.”
وعن الحسن، قال: كان زياد يتبع شيعة علي فيقتلهم فبلغ ذلك الحسن ابن علي، فقال: اللهم تفرده بموته فإن القتل كفارة.

Ubaydullah bin ziyad says that his father killed all the Shia except two
Al-Tabari in Tarikh al-Rusul wa al-Muluk, V5 p361
Ubayd Allah ibn Ziyad said to Hani: “Do you not know that my father came to this city and did not leave anyone from these Shia without killing him, except your father and Hujr?”
فقال عبيد الله: يا هانئ، أما تعلم أن أبي قدم هذا البلد فلم يترك أحداً من هذه الشيعة إلا قتله غير أبيك وغير حجر.

Ibne tamiyah says the khawarij martyred imam Hussain
Ibn Taymiyyah in Minhaj al-Sunnah al-Nabawiyyah, V4 p368
Ibn Taymiyyah explicitly refers to the killers of Imam Husayn (a.s.) as “those Nawasib who killed Husayn.”
أولئك النواصب الذين قتلوا الحسين
