A 31-year-old man was arrested Sunday after a robbery at Heathrow Airport in which 21 people, including a young child, were pepper-sprayed.

Police said a woman’s suitcase was stolen inside a parking-garage elevator by four men who sprayed an irritant, affecting people nearby.

Authorities believe the suspects and victim knew each other and said the incident was not terrorism-related but rather an argument that escalated.

Ambulance crews treated victims at the scene, with five taken to the hospital for non-life-threatening injuries, Fox News has reported.

The incident caused travel delays at the airport, though operations later returned to normal.