The driver of the bus that plunged into a lake in Anshun, Guizhou province, on Tuesday was found to have been holding a grudge after his house was demolished on the same day, Anshun police said in a statement on Sunday.

He had consumed some alcohol that day and intentionally steered the bus across several lanes and through a guardrail before it plunged into the Hongshan Reservoir, which led to the death of 21 people and injured 16.

The driver was among those killed.

After an autopsy and examination of physical evidence, it was determined that the driver, surnamed Zhang, had drowned. Ethanol was found in his body, and 200 milliliters of alcohol was detected in a beverage bottle found at the scene, the police statement said.

An investigation team sent by the city government concluded that Zhang had received no physical or verbal interference while driving. The vehicle involved was an electric city bus that was put into use in October, and it met national standards at the time of the incident and had no mechanical failures, the statement said.

Zhang is suspected of the Criminal Law offense of intentionally endangering public safety, it said.

He divorced his wife in 2016 and lived in a house that he rented from his niece. Police learned that he used to lament that his family was not happy and his life was not satisfactory, according to the statement.

Zhang once worked in diesel engine factory in Anshun's Xixiu district. The factory provided him with a house with an area of 40 square meters, with the factory maintaining property rights. The house was included in a shantytown reconstruction project and was scheduled to be demolished, it said.

According to the investigation, Zhang had not lived in the house for a long time. However, once the project was launched, the project headquarters contacted Zhang to negotiate compensation for the house, the Anshun government said.

On June 8, he signed an agreement with the district's housing authority, which offered him 72,542 yuan ($10,360) in compensation, but he didn't claim it. He also applied for public housing but his application was not approved, it said.

On Tuesday morning, Zhang found the house was being demolished. He then called the government service hotline to complain about the demolition and the rejection of his application for new housing.

At 8:50 am, Zhang, who usually began driving buses at noon, called the shift driver and requested to work earlier.

Zhang bought alcohol from a store, poured it into a nonalcoholic beverage bottle and went to the bus hub to begin his day. He picked up passengers and drove the bus to the terminal railway station at 11:37 am, where they all disembarked. He then called his girlfriend via WeChat, expressing his unhappiness.

At 11:47 am, Zhang started driving again. At 12:09 pm, he was drinking while passengers got on and off the bus. Three minutes later, the bus arrived at the dam of the Hongshan Reservoir. Zhang slowed down at first to avoid other vehicles, then accelerated, crashing through a guardrail and plunging the bus into the reservoir.

The Anshun government said further investigation will be conducted, and any violation of laws and discipline during the process of the house's demolition and the handling of Zhang's complaints will be dealt with strictly.