A police officer has been cleared of any wrongdoing after shooting and killing a civilian at a railway station in northeast China's Heilongjiang Province, said the local police department on Thursday.

The police officer, Li Lebin, shot Xu Chunhe on May 2 at Qing'an County railway station.

An internal investigation found that the shooting occurred in the line of duty and Li had not violated any protocol, said a statement from the railway police in Harbin, the provincial capital, who conducted the investigation.

Xu, 45, was traveling with his 81-year-old mother and three children, when he attacked Li and continued the assault despite multiple warnings before the officer shot him, the statement said.

Xu was confirmed dead by paramedics who arrived at the scene 25 minutes later.

WHAT LED TO THE SHOOTING

Internal police investigators and prosecutors examined the security tape of the incident and interviewed about 60 witnesses. The tape showed Xu, his mother and three children arriving at the railway station on the morning of May 2, when Xu bought tickets to Dalian, a city in neighboring Liaoning Province. The whole family then went to a nearby restaurant for lunch. They returned to the station and entered a waiting room around noon.

Xu's mother, Quan Yushun, told the police that he had drunk a glass of liquor and half bottle of beer at lunch. An autopsy confirmed that Xu's blood alcohol level was 1.28, much higher than 0.8, the official index for being drunk.

At around 12 p.m., Xu blocked the security check passage with a trolley and closed one of the doors to the waiting room. About 40 passengers were stopped from entering the room.

Officer Li was called by a security guard. Despite various warnings and attempts at persuasion, Xu refused to move away from the security passage. When Li opened another door to let passengers in, Xu threw a bottle of water at him.

A struggle followed, during which Xu moved to pull something from his waistband. Alerted, Li drew his gun but did not raise it. Confirming that there was no threat, he replaced the gun in its holster.

Observing that the situation was growing more volatile, Li returned to his office to fetch a baton, closely followed by Xu.

As Li attempted to restrain Xu, he met violent resistance. Having tried to grab the baton, Xu pushed his mother into the officer as she tried to intervene. He then tried to push his daughter towards the officer and the little girl was knocked to the ground.

"He grabbed the baton and hit the policeman on the head. When the policeman pulled out his gun, he struck at his hand. The policeman shouted 'stop' many times, but he just didn't stop," said a witness.

At around 12:06 p.m. officer Li opened fire.

IS IT LEGAL AND NECESSARY TO OPEN FIRE?

Why did the policeman open fire? Was it necessary and legal? How was Xu killed by only one shot? The policeman himself, Li Lebin answered Xinhua's questions.

Li said he drew his gun twice during the incident. He saw a middle-aged man stopping passengers from passing a security checkpoint, and drew his gun when he saw Xu make a move to pull something from his waistband. Li said that Xu shouted, "I will kill you if you dare to arrest me!"

On realizing that Xu had not pulled a knife, Li replaced the gun in its the holster. Recognizing that he could not subdue Xu empty-handed, Li ran to get a riot stick from the duty room, with Xu in pursuit. When Li left the duty room Xu attacked him again, attempting to use both his mother and daughter as a shield. At the time, Li did not know they were Xu's mother and daughter.

"The man's violence became more and more pronounced, so I knew I must control him," Li said. Xu managed to take the riot stick from Li, who then drew his gun again and pointed it at Xu.

"He continued to beat me, hitting me once on my head and again on my hand holding the gun. I believe that the consequences would be disastrous if my gun was taken," Li added. As verbal warnings were ignored, Li opened fire.

Prof. Li He of the National Police University of China, confirmed that it was legal for Li Lebin to have opened fire in those circumstances according to regulations on use of guns by officers.

"The action was decisive, and accurate. The officer had no alternative but to shoot," Li He said. "Xu had not only threatened the life of the officer, but there was a great risk to members of the public if he had not been stopped."

After watching video footage of the event, Xu Chunjing, cousin of Xu Chunhe, suggested that the policeman could have shot another part of Xu's body instead of his heart, or fired a warning shot.

Li Lebin said he had considered a warning shot, but in such a confined situation, the bullet could have ricocheted and inured innocent bystanders. He said he had already warned Xu Chunhe several times.

Li Lebin's words were confirmed by eyewitness accounts.

Xu Chunhe was killed by just one shot. After Li drew the gun, Xu hit him on his gun hand. Li was almost in too much pain to hold the gun and could not aim properly, so he just opened fire in the general direction of Xu.

"I would not have fired if passengers had been behind Xu, but it was only my duty room. No one was behind him," Li added.

Li He said it was unreasonable for the policeman to aim after his wrist had been struck with such force. In the circumstances, it was an accident that the bullet hit Xu in the chest.

WHO WAS XU CHUNHE?

Xu had bought tickets to Jinzhou, a district of Dalian in Liaoning Province.

Xu Chunjing, the dead man's cousin, lives in Jinzhou and believes the family were going to Jinzhou to beg. "They often came to Jinzhou to beg," he said, adding that he once took Xu's children to his home for a bath.

The security footage showed Xu Chunhe talked to no one except his mother and children before blocking the entrance to the security check. The video also shows that he was not touched by anyone, rendering suspicion that he was prevented from entering the train unlikely.

Xu Chunhe's only contact with the outside world from the time he was first seen entering the station was a phone call made to Qian Limin, a man from his home village. Qian said Xu had asked only about whether he had purchased peanut kernels and medicine for kidney disease.

Village officials said Xu Chunhe's family was not impoverished because the assistance provided for was enough to cover their basic living costs.

"Xu's family receive about 6,000 yuan (about 970 U.S. dollars) annually since they transferred the use right of their land to others," said Wang Shuhua, the head of Fengman village, Xu's hometown. "They also get subsistence allowances from the government and substantial aid from the village," Wang added

When asked about why Xu was on his way to Jinzhou, his mother Quan Yushun refused answer. Xu liked drinking very much, she said, and much of the family income was spent on alcohol.

Quan is being treated at a hospital in the county. Her three grand children are now in the care of the local government.