TEHRAN, Iran — Iran said Saturday it executed eight people convicted in the 2017 Islamic State group attack on parliament and the shrine of Ayatollah Ruhollah Khomeini in Tehran.

The June 7, 2017 attack has so far been the only assault by the Sunni extremists inside of Shiite Iran, which has been deeply involved in the wars in Iraq and Syria where the militants once held vast territory.

The judiciary’s official Mizan news agency and semi-official news agencies in Iran acknowledged the executions Saturday, but did not say when they took place. Executions in Iran are carried out by hangings.

The news agencies on Saturday named those executed as Soleiman Mozafari, Esmail Sufi, Rahman Behrouz, Majed Mortezai, Sirous Azizi, Ayoub Esmaili, Khosro Ramezani and Osman Behrouz.

Mizan noted in its report that the executions came after the eight men had been tried and convicted in a trial that included both eyewitness testimony and video footage showing their involvement.

“These eight worked directly … in martyring and wounding a number of innocent compatriots,” Mizan said.

The Islamic State attack killed at least 18 people and wounded more than 50. It saw gunmen carrying Kalashnikov assault rifles and explosives storm the parliament complex where a legislative session had been in progress, starting an hourslong siege.

Meanwhile, gunmen and suicide bombers also struck outside Khomeini’s mausoleum on Tehran’s southern outskirts. Khomeini led the 1979 Islamic Revolution that toppled the Western-backed shah to become Iran’s first supreme leader until his death in 1989.

The assault shocked Tehran, which largely has avoided militant attacks in the decades after the tumult surrounding the Islamic Revolution.

Over a dozen others remain on trial over the attack. Iran’s paramilitary Revolutionary Guard responded to the attack by launching six missiles into eastern Syria targeting IS militants.