Rescuers work at the site of an explosion in downtown Bangkok, capital of Thailand, on August 17, 2015. At least 15 people were killed and more than 80 others injured in an explosion in downtown Bangkok on Monday night, according to local media. (Xinhua/Li Mangmang)

Media staff work near the blast site in downtown Bangkok, capital of Thailand, on Aug. 17, 2015. China's Foreign Ministry has initiated an emergency response after an explosion hit downtown Bangkok Monday night that has killed 19 people, including three Chinese nationals. Photo: Xinhua

An injured person is seen at the Police General Hospital in Bangkok, capital of Thailand, on Aug. 17, 2015. China's Foreign Ministry has initiated an emergency response after an explosion hit downtown Bangkok Monday night that has killed 19 people, including three Chinese nationals. Photo: Xinhua

An ambulance carrying injured people arrives at the Police General Hospital in Bangkok, capital of Thailand, on Aug. 17, 2015. China's Foreign Ministry has initiated an emergency response after an explosion hit downtown Bangkok Monday night that has killed 19 people, including three Chinese nationals. Photo: Xinhua

Police officers arrive at the Police General Hospital in Bangkok, capital of Thailand, on Aug. 17, 2015. China's Foreign Ministry has initiated an emergency response after an explosion hit downtown Bangkok Monday night that has killed 19 people, including three Chinese nationals. Photo: Xinhua

Rescuers arrive at the site of an explosion in downtown Bangkok, capital of Thailand, on Aug. 17, 2015. At least 15 people were killed and more than 80 others injured in an explosion in downtown Bangkok on Monday night, according to local media. Photo: Xinhua

Rescuers work at the site of an explosion in downtown Bangkok, capital of Thailand, on Aug. 17, 2015. At least 15 people were killed and more than 80 others injured in an explosion in downtown Bangkok on Monday night, according to local media. Photo: Xinhua

An ambulance transports injured people due to an explosion in downtown Bangkok, capital of Thailand, on Aug. 17, 2015. At least 15 people were killed and more than 80 others injured in an explosion in downtown Bangkok on Monday night, according to local media. Photo: Xinhua

Photo taken on Aug. 17, 2015 shows debris of glass at the site of an explosion in downtown Bangkok, capital of Thailand. At least 15 people were killed and more than 80 others injured in an explosion in downtown Bangkok on Monday night, according to local media. Photo: Xinhua

Rescuers enter the site of an explosion in downtown Bangkok, capital of Thailand, on Aug. 17, 2015. At least 15 people were killed and more than 80 others injured in an explosion in downtown Bangkok on Monday night, according to local media. Photo: Xinhua

Policemen and rescuers work at the site of an explosion in downtown Bangkok, capital of Thailand, on Aug. 17, 2015. At least 15 people were killed and more than 80 others injured in an explosion in downtown Bangkok on Monday night, according to local media. Photo: Xinhua

Rescuers work at the site of an explosion in downtown Bangkok, capital of Thailand, on Aug. 17, 2015. At least 15 people were killed and more than 80 others injured in an explosion in downtown Bangkok on Monday night, according to local media. Photo: Xinhua

Policemen and rescuers work at the site of an explosion in downtown Bangkok, capital of Thailand, on Aug. 17, 2015. At least 15 people were killed and more than 80 others injured in an explosion in downtown Bangkok on Monday night, according to local media. Photo: Xinhua

The site of an explosion is blocked off by police in downtown Bangkok, capital of Thailand, on Aug. 17, 2015. At least 15 people were killed and more than 80 others injured in an explosion in downtown Bangkok on Monday night, according to local media. Photo: Xinhua

People gather at a BTS Sky Train station near the site of an explosion in downtown Bangkok, capital of Thailand, on Aug. 17, 2015. At least 15 people were killed and more than 80 others injured in an explosion in downtown Bangkok on Monday night, according to local media. Photo: Xinhua

Security members work at the site of an explosion in downtown Bangkok, capital of Thailand, on Aug. 17, 2015. At least 15 people were killed and more than 80 others injured in an explosion in downtown Bangkok on Monday night, according to local media. Photo: Xinhua