A man was Tasered by police after passengers were threatened on a bus with an unknown substance in Thornton Heath.
Officers were called to on Sunday night when the man acted aggressively towards everyone on board.
The passengers all got off safely and the substance was found not to be harmful. Police said than man appeared to have taken drugs.
He was taken to hospital as a precaution where his condition is not life-threatening.
A 44-year-old man was arrested for affray.
Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To Know...