Frankfurt Airport attack: Tear gas incident leaves several people with breathing problems
Police investigating where gas came from as victims treated for inhalation
Several people have been injured by a suspected tear gas attack at Frankfurt Airport in Germany.
Witnesses said the check-in area at Terminal 1 was affected on Monday morning.
Police said six people were being treated for breathing problems after the incident at the country's busiest airport.
"The cause is unclear, investigations continue," a spokesperson added.
Frankfurt Airport operators said the fire brigade's operations had ended and found no "harmful substance" in the departures hall.
Check-in has reopened and flights are operating as normal.
The incident came less than 48 hours after a bomb scare sparked a partial evacuation at Frankfurt Airport.
A man who was believed to be suffering from mental illness told police he was carrying explosives in his luggage but none were found.
A taxi driver had alerted officers to the 37-year-old's strange behaviour and they met him as he arrived at Terminal 1 on Saturday evening.
Local reports said the man was already known to police and has been taken to a psychological ward.
A previous alert was sparked on 31 August after a passenger entered a secure area before completing security checks.
Germany remains on high alert following an Isis-linked terror attack that killed 12 people in December and atrocities across Europe.