Chinese police has launched a manhunt with roadblocks and traffic controls involving land, air and sea transports, following two explosions onboard of public buses in a southwestern city on Monday.  

The blasts that took place in Kunming, the provincial capital of Yunnan, killed two and injured 14.

It was a man-made and deliberate act of sabotage, according to a statement issued by the provincial public security headquarters' press office.
  
Two blasts occurred about half-an-hour apart during the morning rush-hour at 7.10am and 8:05am, according to the statement.

Both the attacks targeted the route 54 intra-city public buses. The first explosion – killing one and injuring 10 – took place along the Renmin West Road, near a side gate of the First Affiliated Hospital of Kunming Medical College.

The second one occurred near the intersection of Renmin West Road and Changyuan Road, resulted in one dead and four injured. Police had released the names of the deceased, a female and male aged 30 and 26 respectively.

The statement added that police had strengthened security and traffic controls of land and sea passage, setting up check posts at major access roads in and out of the province and Kunming city. Security checks for railway and airway too had been enhanced. 

As Yunnan also borders Vietnam, Laos and Myanmar, the police had also mounted more stringent checks at border checkpoints to prevent the culprit from escaping out of the country.

In a later statement by the same public security's press office, the explosive had been identified as ammonium nitrate, which was planted nearer to the front row seats in the first incident and at the back rows in the second blast.

A special task force comprising provincial and municipal officials has been formed to deal with the situation, according to a report by the state media, Xinhua.

The blasts took place amidst tighter security in the run-up to the Olympic Games, which is just 18 days away. The Chinese authorities had earlier warned of possible threat from separatist movement in Xinjiang, in northwestern China.

Just three days before the blasts, the Ministry of Public Security had issued a public manual on terrorism prevention, which can also be downloaded from the internet.

The manual, which comes with illustration, outlined possible means of attack, ways to identify suspicious characters and explosives, potential venues for attack and how to react if an attack occurred, amongst others.