The second attack in less than two weeks targeting a prominent government symbol occurred in Shanxi province yesterday - just days ahead of a key party meeting in Beijing.
The series of explosions that left at least one person dead and at least eight injured near the provincial Communist Party headquarters in the capital Taiyuan was caused by "homemade bombs", Xinhua quoted local police as saying.
The initial police investigation found that "the blast was a deliberate act" as "metal ball bearings and explosive devices made using electric circuit-boards" were found at the site, the news agency said.
Video: Explosions near Shanxi Communist Party headquarters kill one, injure several
The incident occurred even though mainland public security officials were on high alert following last week's suicide attack in Tiananmen Square, which has been officially called a terrorist strike by a Uygur separatist group.
It also came days before top party leaders convene this Saturday for a four-day plenary session that is expected to produce major economic and social policies for the next decade.
No one claimed responsibility for the Taiyuan explosion, as remains the case with the Tiananmen blast.
Resource-rich Shanxi has a noticeable wealth gap between the coal mining executives and the poorer mine workers. On Friday, around 200 laid-off workers protested on the street where the blasts occurred.
The first explosion occurred at around 7.40am when a bomb that had apparently been placed in the flowerbeds almost directly in front of the main entrance of the party's Shanxi headquarters went off, a Shanxi provincial government spokesman said.
Within seconds, a minivan exploded several hundred metres away, according to eyewitnesses. Some mainland media, including the Beijing Youth Daily, reported that seven explosions occurred.
"I thought it was fireworks when the first bomb went off," a witness at the scene recalled. "I realised that it might be some kind of attack, and then I just kept running."
Many bystanders found metal ball bearings and long nails - apparently packed in the bombs as shrapnel - scattered near the blasts.
The injured victims were sent to two hospitals near the blast site. One of the injured was in serious condition and several cars were damaged.
Taiyuan police searched for suspects by asking hotels to report information about guests who checked in on Tuesday night and to monitor every guest in the coming days, three Taiyuan hotels said.
Watch: More of scene from blasts near Communist provincial HQ in China