Usain Bolt had few problems winning the 200-metre title at the track and field world championships on Thursday in Beijing, jumping out to a huge lead after 120 metres and easing past the finish line to take his fourth consecutive gold medal in the event.

But things didn't go as smoothly after the race. In what was clearly a dangerous incident, a cameraman following the sprinter on a Segway ran into a railing and crashed into the Jamaican sprinter from behind.

The Segway took the legs out from under the 29-year-old Bolt, the world's fastest man, and both he and the cameraman crashed to the ground. Fortunately both men were not injured and Bolt was soon joking about the incident. 

The footage of the post-race collision was soon doing the rounds on social media.

It was the fifth-fastest 200-metre time ever for Bolt, who set the world record in the event (19.19 seconds) at the 2009 world championships. He has won every 100-metre and 200-metre event at the Olympics or world championships since 2008, save for the 2011 world championships when he was disqualified for a false start in the 100-metre final.

Justin Gatlin, 33, became the oldest sprinter to ever medal in the 200m at the world championships.

He has finished behind Bolt in three consecutive 200-metre championship races, winning bronze at the 2012 Olympics and silver at the 2013 world championships.

Gatlin was also second to Bolt in the 100m at these world championships.

And the near-disaster with the Segway wasn't the only weird thing that happened after the race. A couple of young fans jumped onto the track to get a selfie. It didn't work.