One explosion at 7:05 a.m. on a commuter bus was followed by another an hour later on a bus downtown.
Chinese police have not yet given any explanation other than to say that the attacks were "sabotage," according to the New China News Agency.
There were unconfirmed reports in Chinese state media that there had been a third explosion.
Passengers on the second bus told a local newspaper, Life Daily News, that they saw two men leave an unidentified object on board.
"Later, two men got off the bus, then it exploded. One-third of the bus was seriously damaged. The fire wasn't very big, but the smoke was dense and there were strong odors," the newspaper reported. One person was killed in the second bus explosion, and two in the earlier one.
Article on the International Herald Tribune is here.
Photos are from Chinese BBS wnxuecity.com