On the evening of August 17, 2008, an attacker threw a grenade through a window of the Abu Bakr mosque (Əbübəkr Məscidi) in central Baku, Azerbaijan, during evening prayer. The explosion killed three people and injured eleven others. The mosque was known to be used by both Sunni and Wahhabi Muslims, according to Reuters reporting cited in the case summary.
The attack occurred against a backdrop of heightened concern in Azerbaijan about extremist activity. The U.S. Department of State's annual Country Report on Terrorism for 2008 described Azerbaijan as "a logical route for extremists with ties to terrorist organizations." In the months prior to the bombing, Azerbaijani authorities had launched several investigations into Wahhabism in the country, and law enforcement had previously determined that individuals convicted of an attempted terrorist act in the town of Sumgait had links to al-Qaeda. Despite controversy surrounding Wahhabist activity in Azerbaijan, the government stated that Wahhabi groups would not be banned. Following the mosque bombing, both the United States and Israeli embassies in Azerbaijan expressed concern about the incident.
In response to the attack, Azerbaijani authorities created a special committee to handle the investigation, and the mosque was closed for the duration of that investigation. The Ministry of National Security of Azerbaijan accused leaders of the Russia-based jihadist group Derbent Jamaat of organizing the attack, naming Ilgar Mollachiyev, from Zagatala, and Samir Mehdiyev (also known as Suleiman), along with a group of other individuals. The Ministry stated that, according to the group's plan, a "Sumgayit Jamaat" — described as a secret extremist group — was to be created, and that the group had planned a number of robberies in Baku to collect funds for jihad. This connects to an earlier 2007 case in which 17 members of the group were arrested in Sumgayit.
Following the bombing, Azerbaijani security services launched Operation Eagle in response to the attack and the accusations against Derbent Jamaat.