The Scotland Yard counterterrorism command launched an investigation on Tuesday night after three suspicious packages containing improvised explosive devices were received at three locations in London, including near Heathrow.
No arrests were made and there were no interruptions on the flight, but police said the command is treating the incidents as related and keeps an open mind to the investigations. The packages were white A4 size postcards.
The packages were evaluated by specialized officers as small improvised explosive devices that seemed able to light an initially small fire when they opened.
The first package was discovered in a building in Hounslow, near Heathrow. It was opened by the staff, which caused the device to start, which caused part of the package to burn. Specialized agents attended and secured the device, police said.