Federal and local authorities said Tuesday they are investigating who placed explosive devices made from dry ice at the Los Angeles International Airport.
Officials said no one was injured and no damage was caused when two of the devices exploded.
One went off late Sunday, while a second exploded overnight Monday into Tuesday, authorities said.
Two other dry ice bombs were discovered before they exploded, according to authorities, who said they do not believe they are linked to terrorism.
The devices, fashioned from dry ice placed inside bottles, were found in restricted areas of the airport that the general public does not generally have access to, officials said.
The investigation is being carried out by the Los Angeles Police Department and the FBI.