The arrests were made in Alborz province's Fardis town, reports Xinhua news agency.
Suicide bombers and gunmen attacked the Iranian parliament and Ayatollah Khomeini's mausoleum in Tehran on Wednesday, killing at least 13 people and wounded 43 others, according to Iran's Interior Ministry.
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An Iranian judicial official says eight more individuals have been arrested in Iran in connection with the recent terrorist attacks in the capital, Tehran. At least 17 people lost their lives and almost 50 others were wounded in the assaults, which involved shootings and blasts.
The attackers managed to get inside the building and engaged in a shootout with the security forces.
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On Friday, Intelligence Minister of Iran Mahmoud Alavi said that investigators were working to determine whether Saudi Arabia had a role in Wednesday's attacks but said it was too soon to say if that was the case.
The terrorist group of Daesh (ISIS) has claimed responsibility for the fatal attacks in Tehran. During the operation to arrest the terrorists, large amounts of weapons, bomb-making materials, explosive belts, communication equipment, and forged documents had also found, it added.
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Tehran police said the vehicle the attackers used for both attacks was discovered on Saturday in the city center. Sending a tough message to Tehran shortly after pragmatist Hassan Rouhani was re-elected president, Trump urged Arab leaders to unite to defeat militants, and said Iran had for decades "fueled the fires of sectarian conflict and terrors".