A dry ice bomb exploded at Los Angeles International Airport Sunday night—and yesterday, three similar bombs were found, including another one that exploded last night, the LA Times reports. The first bomb was placed in a restroom the public cannot access, and the devices found yesterday were also in an employees-only area, outside and near a plane parked at a gate in the international terminal. No one was hurt. An LAX spokesperson tells NBC News the devices, plastic bottles with dry ice inside, are "harmless." Even so, the LAPD is investigating, with help from the FBI.