Police arrest five suspects over Tehran attacks
"After the attack in the mausoleum of Ayatollah Khomeini, five suspects were arrested by the police ... They are under investigation," Hossein Sajedinia was quoted as saying by ISNA news agency.
Separately, the deputy chief of the Guards' Intelligence Service, Mohammad Hossein Nejat, told the Fars news agency that the men who attacked the parliament building in Tehran were aged between 20 and 25.
"(They) went to the parliament as visitors. The guards became suspicious of their bags and when they wanted to search them, shooting began and they killed the security guard," he said.
He said the men spoke Arabic in a video released by IS from inside the building, but that their nationality was not yet known.
Thirteen people were killed and more than 40 injured in the attacks on Tehran's parliament complex and the shrine of revolutionary founder Ayatollah Ruhollah Khomeini.
Islamic State group claimed the attack via its propaganda news agency Amaq.