The attack hit the Shah Cheragh Shrine in the southern Iranian city of Shiraz, with at least two children killed.
At least 15 people have been killed and 40 others injured in an attack on a Shia religious shrine in the southern Iranian city of Shiraz, according to the country’s state media agency, IRNA.
The report said that the attack, which took place at the Shah Cheragh Shrine early on Wednesday evening, was carried out by three armed men who entered the shrine.
ISIL (ISIS) claimed responsibility for the attack in a statement on their telegram channel.
Nour news, a media outlet affiliated with the Iranian state, had earlier reported that the attackers were not Iranian nationals.
The Fars News Agency said that one woman and two children were among those killed in Shiraz.
“We were preparing for prayers and then we heard the gunshots, we tried to escape from the other side and then I realized I was bleeding,” a witness and survivor of the attack told Al Jazeera.
“I could not see who was shooting … It started from the street and then they came towards the shrine and they shot whoever they saw. I saw some injured and killed, but I did not see the attackers,” he said.
Fouad Izadi, an associate professor in the Faculty of World Studies at the University of Tehran, said the aim of the shooting was to “attack worshippers”.
“This is an ISIS trademark – they attack mosques, they attack shrines,” Izadi said.
Al Jazeera’s Dorsa Jabbari, reporting from Tehran, said that the shrine was an important site for religious pilgrims.
Shiraz is a popular destination for pilgrimages and tourism, and the last such attack to take place in the city was in April 2008, when a bomb planted in a mosque killed 14 people.
“This is a very rare incident to be taking place at a very important time in Iran, when security is at high alert given the number of protests that have been taking place across the country,” Jabbari said.