ISIS claimed responsibility for twin attacks in Iran’s capital on Wednesday, one at the country’s parliament building and another at the shrine of Ayatollah Khomeini, the founder of the Islamic Republic of Iran.

At least 12 people are dead and several more are injured, according to the BBC.

A stand-off with possible hostages at the legislature, where parliament was in session, is believed to be still underway.

The attacks began mid-morning when gunmen stormed the parliament building in Tehran. One of the assailants later blew himself up inside, according to a statement issued by Iran’s state news agency, IRNA.

An ABC News reporter in Tehran said he heard gunfire Wednesday afternoon, and shops in the area remained shuttered.

A suicide bomber and other attackers also targeted the shrine of Khomein, located just outside the capital.

Iran’s Deputy Interior Minister Mohammad Hossein Zolfaghari told IRIB the male attackers wore women’s attire.

Through its Amaq News Agency, ISIS claimed its fighters were behind the twin attacks, which would be the terror group’s first within Iranian territory.