BEIJING Chinese police are investigating a bizarre text message warning residents of Kunming to avoid buses hours before two bomb blasts killed two passengers in the Monday rush hour, local media reported.
The attack, which came amid a nationwide security clampdown ahead of next month's Beijing Olympics, also injured 14 people in the city, capital of the mountainous southwestern province of Yunnan.
Some residents received phone text messages in the early hours of Monday, the Southern Metropolis Daily said, presumably written on Sunday.
"The general mobilization of ants... (I) hope citizens receiving this message will not take bus lines 54, 64 and 84 tomorrow morning," the newspaper quoted the message as saying.
The explosions, which came within one hour of each other, hit two line 54 buses close to each other, blowing holes in the side. In both cases, ammonium nitrate was wrapped under the seats.
"It is really strange... did he really want to warn us?" a woman surnamed Feng was quoted as saying.
One of the injured passengers was in critical condition, while most of the others suffered shattered eardrums, state media said.
Police have started roadside checks in Kunming and have stepped up security across Yunnan. A team of experts has also arrived from Beijing.
Police have also offered a reward of 100,000 yuan ($14,660) for any information leading to solution of the case, Xinhua news agency said.
The attack happened less than three weeks before the Aug 8-24 Beijing Games, which China has warned could be a target of terror attacks.
Chinese Foreign Ministry spokesman Liu Jianchao condemned the blasts, but said there had been no evidence to link them with terrorists.
"There has been no evidence so far to show that the incident is related to the upcoming Beijing Olympics," Liu said at a news conference.
China has occasionally witnessed bus explosions staged by disgruntled farmers or laid-off workers wanting to air grievances over poverty, demolitions or corruption.
(Reporting by Guo Shipeng and Benjamin Kang Lim; Editing by Nick Macfie)