LONDON — A man was arrested on Sunday after a “group of men” unleashed what may have been pepper spray in a parking garage at London’s Heathrow Airport, the police said.

The incident was not being investigated as terrorism, Cmdr. Peter Stevens, of London’s Met Police, said in a statement. Officers were called just after 8 a.m. local time to the parking garage at Terminal 3, where there were reports of “multiple people being assaulted,” the department said.

“A number of people were sprayed with what is believed to be a form of pepper spray by a group of men who then left the scene,” the police said.

The man who was detained, who was not immediately identified, remained in custody on suspicion of assault, the police said.

“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.

Police said people were transferred by ambulances to local hospitals with injuries that were thought to be non life-threatening. Officials did not say immediatly how many people had been injured.

Terminal 3 remained open, although there was “some disruption of traffic” in the area near the parking garage, police said.

Stevens in his statement said the department planned to increase the presence of officers throughout the airport, which is among the busiest in Europe, for the remainder of the morning.

“Passengers are advised to allow extra time when travelling to the airport and to check with their airline for any queries,” Heathrow said on social media.

ABC News’ Mike Trew and Jessica Gorman contributed to this report.