The middle-aged man, whose identity was yet to be confirmed, forcibly prevented passengers from going through the security inspection gate at Qing'an Railway Station in Suihua City, a spokesman with Harbin railway police authority told state-run Xinhua news agency.
When a policeman on patrol tried to stop him, the man picked up a child and threw him at the police.
In the chaos, he also tried to grab the policeman's gun and club.
The spokesman said police opened fire to keep the passengers safe.