SHANGHAI, June 12, 2016 -- An armed policeman stands guard at the site where an explosion happened at Shanghai Pudong International Airport in east China's Shanghai, June 12, 2016. Three passengers were injured after an explosion at Shanghai Pudong International Airport on Sunday afternoon, authorities said. (Xinhua/Ding Ting)

SHANGHAI, June 12 -- Four people were injured in an explosion at Shanghai Pudong International Airport Sunday afternoon, authorities said.

The accident happened at around 2:20 p.m. near a check-in counter in Terminal 2, when what appears to be a homemade explosive blew up, according to Shanghai Airport Authority, which manages the airport.

The injured are receiving treatment at the Pudong New District People's Hospital.

One of the injured sustained a severe neck injury, according to the hospital. An initial investigation has found evidence suggesting that the man's injury could have been self-induced.

The other injured include a 53-year-old Philippine man, as well as a 67-year-old man and a 64-year-old woman, both of whom are Chinese. They sustained injuries to their heads, hands and legs, doctors said.

The investigation continues.