Iran's intelligence minister said the mastermind behind Wednesday's attacks in Tehran, which killed 17 people, had himself been killed on Saturday by security forces.
"The mastermind and main commander of terrorist attacks on the parliament and Mausoleum of Ayatollah Khomeini was killed today by the security forces," Mahmoud Alavi was quoted as saying by Tasnim news agency.
The jihadist group Islamic State had claimed responsibility for the attack, by suicide bombers and gunmen.
Iran said on Thursday that gunmen and bombers who attacked Tehran on Wednesday were Iranian members of ISIS who had fought in the militants' strongholds in Syria and Iraq – deepening the regional ramifications of the assaults.
An Iranian journalist claimed on Twitter that a woman arrested by authorities was a mastermind behind the attacks. It was unclear who was killed Saturday.
Police, who said they were holding six suspects as part of their investigation into the attacks, also increased their patrols in the streets and subway stations of Tehran on Thursday.
The move comes a day after a pair of ISIS-claimed attacks on Iran's parliament and the tomb of its revolutionary leader killed at least 13 people and wounded over 40.
Mohammad Hossein Zolfaghari, a deputy Interior Minister, told state TV that "law enforcement activities may increase” and added that authorities are “focused on intelligence” gathering.
The bloodshed shocked the country and came as emboldened Sunni Arab states – backed by U.S. President Donald Trump – are hardening their stance against Shi'ite-ruled Iran.
The White House released a statement from Trump condemning the terrorist attacks in Tehran and offering condolences, but also implying that Iran is itself a sponsor of terrorism.
"We grieve and pray for the innocent victims of the terrorist attacks in Iran, and for the Iranian people, who are going through such challenging times," the statement said. "We underscore that states that sponsor terrorism risk falling victim to the evil they promote."
The comments sparked anger from Iranians on social media, who recalled the vigils in Tehran that followed the September 11 attacks. Iranian Foreign Minister Mohammad Javad Zarif in a tweet on Thursday called the White House comments "repugnant" and accused the U.S. of supporting terror.
"Iranian people reject such U.S. claims of friendship," Zarif tweeted.
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