French Prime Minister Manuel Valls said Monday the government knew that the attacks in and around Paris, which killed at least 129 people and injured nearly 350, were being planned and that more are in the planning stage, not just in France but across Europe. He also confirmed that police conducted searches of suspected Islamists in the country, who may be related to Friday’s attacks, Reuters reported.

According to local reports, police officials have arrested six people from the eastern city of Grenoble and three from the southern city of Toulouse during anti-terror raids over the weekend. About 150 searches were conducted across the country, according to local news network BFMTV.

Police officials also seized weapons and cash from Grenoble, iTele, a local news network, reported. A reporter for BFMTV tweeted that five people have been arrested in the eastern city of Lyon, from where officials also seized weapons, including a rocket launcher.

Earlier reports said that about 20 people, besides the eight attackers, across Europe could have been involved in planning the six attacks. The reports added that several suspects are likely to have been hiding in Molenbeek, a suburb of Brussels, which is of late being considered as the hotbed for training radical Islamists.

Two attackers have so far been identified -- as Ismaël Omar Mostefai and Abbdulakbak B. -- by French police officials. Seven of the attackers died in suicide bombings while the eighth suspect died after being shot by police.

The attacks in France, including one on Bataclan theater, led to security levels in the country being raised and borders being closed. French authorities also launched a series of airstrikes using 10 jets and 20 bombs on the Islamic State group stronghold of Raqqa, Syria, as ISIS claimed responsibility for the attacks.

French President François Hollande has declared the attacks as “an act of war,” calling them the worst in the country since the Second World War.