A 31-year-old man was taken into custody by police at a London airport on Sunday, in connection with a robbery that left 21 individuals, including a toddler, needing medical assistance after being exposed to pepper spray, authorities confirmed.

The robbery unfolded in the morning at Heathrow Airport’s parking structure. According to the Metropolitan Police, four men were involved in the theft of a woman’s suitcase inside an elevator, during which they deployed an irritant towards her.

“The woman’s suitcase was stolen by a group of four men who used what is believed to be pepper spray,” stated Commander Peter Stevens. He noted that the attack also impacted bystanders within the elevator and nearby areas.

Following the incident, the offenders made their escape from the elevator. Witnesses, as reported by The Associated Press (AP), described the suspects as three young men dressed entirely in black, concealing their heads.

Armed officers hurried through the Heathrow Airport parking garage after receiving reports of the pepper-spray attack. (Tom Bate/Reuters)

Video captured a swarm of officers rushing to the scene of the assault, visibly carrying large firearms as they navigated the multi-story parking garage.

Authorities said the victim and the suspects knew each other, and investigators are not treating the case as a terrorism-related incident.

“At this stage, we believe the incident involved a group of people known to each other, with an argument escalating and resulting in a number of people being injured,” Stevens said.

An emergency vehicle outside Heathrow Terminal 3. (Andrew Matthews/PA Images)

“We are not treating this incident as terrorism,” he added. “I understand the public’s concerns and would like to thank those in the area for their cooperation this morning.”

Officials said the 31-year-old is being held on suspicion of assault, and that authorities are searching for the other suspects who escaped.

Police officers look down from an upper level of a Heathrow Airport parking garage while searching for suspects in a pepper-spray assault. (Tom Bate/Reuters)

Ambulance crews treated victims at the scene and transported five to the hospital. Their injuries are not believed to be life-threatening, according to the authorities.

The incident led to hours of travel delays for passengers arriving at and departing from the airport, the AP reported, but operations have since returned to normal, according to the airport in a post on X.

Fox News Digital reached out to the Metropolitan Police and Heathrow Airport for more information.