Unidentified gunmen opened fire in a mostly Shia area in eastern Saudi Arabia on Monday night, killing five people and wounding nine others. The shooting coincided with the eve of Ashoura, an Islamic day of remembrance of the death of Imam Hussein, which holds particular significance for Shia Muslims. 

Using the hashtag #اطلاق_نار_الاحساء (al-Ahsa shooting), Saudis sent more than 250,000 tweets discussing the incident, and warning of potential implications, including a rise in sectarianism.