The Ministry of Public Security (MPS) on Tuesday vowed to investigate a police shooting case in Northeast China's Heilongjiang Province amid rising demands for local authorities to offer further information on the death of an alleged petitioner.

The MPS promised to announce the results as soon as possible, the Xinhua News Agency reported.

Xu Chunhe, 54, was shot dead by a police officer at a railway station in Heilongjiang's Qing'an county on May 2 while passing through a security checkpoint. According to China News Service, Xu allegedly stopped other passengers from entering and also grabbed and threw a young child at a police officer while trying to snatch the officer's gun.

A statement from the MPS said railway police authorities had sent investigators to Qing'an. Prosecutors are also involved, Xinhua reported.

The investigation team and prosecutors have begun contacting witnesses and collecting evidence after checking video tapes related to the incident, and have interviewed dozens of travelers and local residents in recent days, according to the statement.

As media reports have revealed more details about the case, more questions have been raised, including whether Xu's death was related to his previous petitions. Xu had reportedly petitioned for local authorities to make arrangements for his mother in her 80s to live at a nursing house and for the three children of his - all of whom are under 10 - to live in a welfare home due to his inability to look after them. According to Guangdong-based newspaper Nandu Daily, Xu was recognized by security staff as a petitioner and his family were then stopped for fear that they were seeking to lodge another petition.

An increasing number of media outlets, including Xinhua, have published opinion pieces recently demanding that local authorities release security camera footage and the results of their internal investigations.

Meanwhile, online discussions of the incident multiplied, as netizens expressed their doubt that police needed to use their firearm on Xu, especially following the appearance of an unverified video clip showing police beating Xu with batons.

In response, the MPS statement said there are clear rules on the carrying and use of fire arms by police officers, and it will take time to confirm whether police had opened fire legally in the case.

Local authorities had previously praised the police officer who shot Xu for "protecting lives" and "public property," according to news portal qartv.cn. An earlier Xinhua report quoted Zhao Dongbin, a police officer from the railway public security department, as saying that Xu was shot after ignoring police warnings.

Chinese police can use their weapons if suspects ignore warnings or threaten public security, according to regulations.

Meanwhile, Dong Guosheng, deputy head of Qing'an county, has been suspended from his post and probed for faking his diploma and arranging for his wife to receive a salary during a sick leave of nearly four years. Both allegations began to go viral due to online tip-offs after the shooting.