Security forces on Monday sealed off the streets and a bomb squad was deployed in the Paris suburb of Montrouge after investigators found what looked like a suicide vest in a garbage can. CNN reported that authorities were trying to establish if it contained explosives. BFMTV, a local channel, claimed the item contained bolts and TATP, the same explosive found in the suicide belts used by Paris attackers on November 13.

The police have launched a massive manhunt to catch one of the suspects, Salah Abdeslam, who was allegedly involved in the Paris raids, but has proved to be elusive so far. The Wall Street Journal reported that the police suspect the vest might have belonged to Abdeslam, and that he aborted his suicide mission and fled. Extensive raids in Belgium were carried out on Sunday and Monday with the capital in lockdown, and at least 21 people were detained.

The United States, meanwhile, issued a worldwide travel alert warning its citizens of the risks of traveling in the wake of "increased terrorist threats," on Monday. "Current information suggests that Islamic State, al-Qaeda, Boko Haram, and other terrorist groups continue to plan terrorist attacks in multiple regions," the department said in a warning posted on its website.