Five of the men who launched an attack in the heart of Iran's capital previously fought for the Islamic State group, the country's Intelligence Ministry said Thursday, acknowledging the first such assault by the extremists in the Shiite power.

The attacks Wednesday on Iran's parliament and the tomb of its revolutionary leader killed at least 17 people and wounded over 40, stunning its people.

The ministry issued a statement on its website with bloody pictures of the men's corpses. It identified them only by their first names, saying they didn't want to release their last names due to security and privacy concerns for their families.

It described them as "long affiliated with the Wahhabi," an ultraconservative form of Sunni Islam practiced in Saudi Arabia. However, it stopped short of directly blaming the kingdom for the attack, though many in the country expressed suspicion Iran's regional rival had a hand in the attack.

The men had left Iran to fight for the extremist group in Mosul, Iraq, as well as Raqqa, Syria _ the group's de facto capital, the ministry said. It said they returned to Iran in August under the command of an Islamic State leader and escaped when authorities initially broke up their extremist cell.

The ministry did not identify the men's hometowns, nor say how they were able to evade authorities. A woman suspected to be involved in the attack was arrested Wednesday.

Commuters in the Iranian capital noticed police on street corners and motorcycles, more than usual as dawn broke. That came after Mohammad Hossein Zolfaghari, a deputy Interior Minister, told state TV that "law enforcement activities may increase."

"We are focused on intelligence" gathering, he said.

The state-run IRNA news agency also reported Thursday that the death toll in the attacks had risen to 17 people killed, citing Ahmad Shojaei, the head of the country's forensic center.

The attack Wednesday as lawmakers held a session in parliament and at the shrine of Ayatollah Ruhollah Khomeini shocked Iranians who so far had avoided the chaos that has followed the Islamic State group's rise in Syria and Iraq. Iranian forces are backing embattled Syrian President Bashar Assad while the Shiite power also is supporting militias fighting against the extremists in Iraq.

The attack came as emboldened Sunni Arab states _ backed by US President Donald Trump _ are hardening their stance against Shiite-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." (AP)