The official Xinhua news agency blamed the blasts on "sabotage" and said police had started roadside checks in Kunming, the capital of Yunnan province, to try to find the person or persons responsible, Reuters reported.
Reports varied as to the number of buses involved in the apparent attacks, with some media organizations reporting three explosions and others reporting only two. The blasts occurred during the height of morning rush hour traffic.
The first blast occurred at about 7 a.m. local time at a bus stop on Renmin West Road, a major Kunming artery, killing one woman and injuring 10 other people, police said, according to Agence-France Presse
"The glass on both sides of the vehicle was all shattered and some of the seats were warped," they told the news agency.
While violent acts are generally rare in China, the country has previously seen attacks on buses and other public venues by farmers upset over land use policies or by others protesting economic policies.
Li Wei, director of the Center for Counter-Terrorism Studies at the China Institute of Contemporary International Relations in Beijing, told the Washington Post that not enough was known about the blasts to deem them acts of terrorism.
"People will think the aim is the Olympics," Li said. "But this case might be caused by social conflict or some individuals who have some extreme ideas."
Tensions have erupted in Yunnan province in recent months between local rubber farmers and a private distribution firm. Monday's blasts come two days after Yunnan police opened fire and killed two rubber farmers in the province's Menglian county in a clash that also saw 41 police officers injured, according to Reuters.
Beijing has worked to clamp down on security ahead of the Summer Games by activating a large anti-terror force and beefing up security efforts in the five cities hosting Olympic events.
Officials have warned of possible terrorist threats as the Games, which will be held Aug. 8-24, have neared, including from Muslim militants in China's restive northwestern Xinjiang region and from Tibetan independence supporters.
