KUNMING, July 22, 2008 -- There was no evidence to show that two bus explosions that killed two people and injured 14 on Monday in Yunnan Province were connected to terrorist attacks or aimed at next month's Olympics, a local official said here on Tuesday.

Du Min, vice mayor of Kunming, the Yunnan capital, said at a press conference it remained unclear whether the blasts were conducted by many people, or one individual.

bus hit by an explosion is seen in Kunming, capital of southwest China's Yunnan Province, July 21, 2008. Two people were killed and 14 others injured in two separate explosions on public buses in downtown Kunming on Monday morning.  (Xinhua Photo)

Police still had no clues to the backgrounds of suspects and were investigating the case, said Du, also the Kunming Public Security Bureau chief.

The explosions occurred on two Route 54 buses during Monday's morning rush hour in Kunming. One blast was on West Renmin Road at 7:10 a.m., while the second was at the nearby intersection of Changyuan Road and West Renmin Road at 8:05 a.m.

"This is the worst case that has occurred in Kunming in 30 years," Du said.

In a local rumor going around two to three hours prior to the blasts, some residents had received a text warning message saying "Citizens who receive this message are advised not to ride the buses of routes 54, 64 and 84 the next morning."

"In fact, there was no such a text message," Du said.

The bureau has announced a reward of 100,000 yuan (about 14,280 U.S. dollars) to anyone who offers information that can help solve the case.