The Karte Sakhi Mosque in Afghanistan was attacked Tuesday by heavily armed gunmen during a religious ceremony attended by hundreds, according to a release by the U.S. Embassy in Kabul. The attackers entered the Shiite shrine and opened fire on parishioners worshipping during the Shiite holy day of Ashura.

The Embassy believes that the insurgents, possibly wearing military uniforms, took hostages throughout the ordeal. Initial news reports said eight people may have been killed in the assault, according to Sputnik News. The Afghan Interior Ministry later said 14 were dead.

"A number of attackers have targeted people in Karte Sakhi shrine," said Kabul Police chief Abdul Rahman Rahimi. "Police have evacuated dozens of people from the shrine. A number of civilians and police have been injured."

Interior Ministry spokesperson Sediq Sediqqi said all three gunmen were shot dead by police. There were conflicting reports about the number of casualties. Public Health Ministry spokesperson Ismail Kawasi said 26 were wounded and taken to the hospital. At least police officers were injured in the attack. 

Authorities warned about avoiding large gatherings during the Ashura procession. In July, 80 Shiite Hazaras were killed in twin explosions in Kabul. In 2011, the Abu Fazl Mosque in Kabul was the scene of a massive coordinated bombing that also targeted Shiite worshippers during Ashura, killing over 60. Pakistani terrorist group Lashkar-i-Jhangvi claimed responsibility for the attack.

Ashura is the tenth day of the Islamic month of Muharram, when Shiite Muslims remember Husayn bin Ali, the grandson of the Prophet Muhammad who was martyred during the Battle of Karbala in 680 AD.

Shiites make up about 15 percent of Afghanistan's population of 30 million people. 

95600326 An Afghan man and woman walk in front of the Karti Sakhi Shrine in Kabul on Jan. 6, 2010. Photo: Getty Images

135162555 Afghan men cary the coffin of a victim of a bomb attack against Shiite Muslims outside the Karti Sakhi Shrine in Kabul on Dec. 7, 2011. Photo: Getty Images