Emergency crews gathered outside the Ginza Six shopping complex after a spraying incident injured shoppers in central Tokyo.
Video showed fire engines, police and emergency workers surrounding the mall as stretchers were brought outside and roads in the Ginza district were blocked off.
Japanese authorities said a man sprayed an unidentified substance near an ATM area inside the building, leaving around 20 people suffering symptoms including throat irritation.
Officials said 19 people were taken to hospital and all were conscious. Police are investigating the incident.
