As investigators hunt for leads in Europe's worst terror attack in a decade, the Paris prosecutor laid out how three teams of assailants managed to kill at least 129 people in and around one of the world's most heavily policed capitals.

Suicide bombers and gunmen linked to the Islamic State group "were behind how the terrorist acts unfolded," Francois Molins said in a televised press conference late Saturday.

At least one perpetrator was a French citizen, and police found a Syrian passport beside another, who blew himself up outside the Stade de France during a France-Germany soccer match, Molins said. In Belgium at least three people have been arrested in connection with the deadly attacks, local prosecutors said.