HONG KONG (AP) _ A bus exploded in the central Chinese city of Wuhan today, killing 16 people and injuring 30 others, a Chinese news agency reported.

But a Hong Kong-based dissident group quoted an unidentified source in Wuhan as saying at least 30 people were killed in the explosion, which it said was believed to have been caused by a bomb.

The China News Service, monitored in Hong Kong, said the explosion occurred when the bus was approaching a bridge in the city in Hubei province.

It said traffic in the area was halted for four hours, and that officials were investigating the cause of the explosion.

The Hong Kong-based Information Center of Human Rights and Democratic Movement in China quoted its source as saying that the bus was gutted by fire after the explosion.

In a statement, the group said two taxis and three other buses were also damaged in the blast. The group is known to have good sources in China's dissident community.

No other details were available.