A man has been hurt after apparently detonating a homemade bomb in an arrivals hall at Beijing International Airport.
Pictures posted on the Chinese equivalent of Twitter, Weibo, showed smoke in Terminal 3 after the blast at around 6.30pm local time.
Witnesses have claimed that a man was sitting in a wheelchair in the arrivals hall, shouting and waving a small bag in the air before the explosion took place.
The Weibo microblog of state broadcaster China Central Television (CCTV) said a man detonated a package of black gunpowder used to make firecrackers just outside the international arrivals exit.
Photos taken in the minutes after the explosion showed a wheelchair lying on its side, medical workers attending to someone and people running through the terminal.
A man, who local media named as Ji Zhongxing, who was born in 1979 and in Shandong Province, was injured in the blast and has been taken to hospital.
No one else was hurt in the incident and airport operations are now back to normal.
"The explosion sound was loud," said a witness who gave only his family name, Chen. He said he was only 25m away from the explosion when it occurred.
Chen said there was only one explosion, and that the terminal was crowded with people.
"Since there was no second explosion, many people took out their phones and gathered near the explosion spot to take photos," he said.
He said police responded to the explosion immediately.
Sky's China Correspondent Mark Stone, at the airport, said the man may have travelled to the capital to petition for a particular social cause.
"This is looking like a tragic story really. There are a lot of people in China who call themselves 'petitioners'.
"Every now and again they go a little bit further and it's a very much more extreme form of petitioning and that I think, is what this appears to be."
Stone said most petitioners complain of local corruption, land grabs and beatings.
He added that a blog purporting to have been written by the man contains claims he was beaten and paralysed by Chinese police in 2005. This has not been verified.
Terminal 3, which opened in 2008 just ahead of the Beijing Olympics, is the airport's hub for international flights. United Airlines and American Airlines operate out of the terminal.