London: A counter-terrorism investigation was launched after three small improvised explosive devices (IED) were found at Heathrow Airport, City Airport and Waterloo station, said the UK police on Tuesday.

According to the London Metropolitan Police, the three devices sent to the above-mentioned airports’ stations are capable of igniting an initially small fire when opened. “The Met Police Counter Terrorism Command is treating the incidents as a linked series and is keeping an open mind regarding motives,” read the statement further.

The Met Police said: “The packages – all A4-sized white postal bags containing yellow Jiffy bags – have been assessed by specialist officers to be small improvised explosive devices.

While one mailer was found near Heathrow Airport, another mailer turned up near City Airport, and the third in the mailroom at Waterloo Station. A building at the Heathrow Airport was evacuated as a precaution after the package was opened and part of it burned.

As per reports, no one was injured by the devices and the services remained unaffected.