HONG KONG—Chinese authorities said 302 people had died during severe flooding that hit the central province of Henan last month, a sharp increase in the death toll that comes as rescue workers extract more bodies from the provincial capital Zhengzhou and the surrounding countryside.

The death count makes the disaster one of the deadliest in China in recent years, with 50 people still missing, Henan provincial authorities said at a briefing Monday. The death toll marked a threefold jump from the official figure of 99 deaths released Thursday last week.

Henan province was battered by record rainfall in late July, with nearly a year’s worth of rainfall pouring down on the city in the span of three days, according to meteorological officials in Zhengzhou. The city of more than 12 million residents was among the worst-hit areas, accounting for more than 95% of all deaths.

Local news reports and social-media posts showed inundated neighborhoods and harrowing scenes of commuters stuck chest-deep in flooded subway cars. Out of more than 500 passengers trapped during the evening rush hour in the metro, at least 14 people ended up dying.

Earlier

Record rainfall in central China triggered flooding that swamped subways and forced about 100,000 people to relocate. Henan province is a major base for industry and home to one of the world’s biggest iPhone-manufacturing sites. Photo: AFP/Getty Images The Wall Street Journal Interactive Edition

According to Henan’s provincial government, 189 people were killed in the city of Zhengzhou alone due to flooding and mudslides, while another 54 residents died when houses collapsed due to the torrential rain.

One of China’s most populous and least developed provinces, Henan is home to more than 99 million residents and an economy reliant on agriculture and industry. The province has accounted for around 10% of China’s grain output in recent years, according to analysts, though China’s Ministry of Agriculture and Rural Affairs has said that the flood’s impact on the country’s overall grain supply was limited. On Monday, Henan officials said the flood had resulted in the equivalent of $17.7 billion in direct economic losses.

China’s cabinet, the State Council, has set up an investigation team to evaluate Zhengzhou’s response to the floods and to propose improvement measures, the state-run Xinhua News Agency said Monday. The team will also identify individuals who neglected their duties and hold them responsible, the report said.

Government officials have blamed the flooding of Zhengzhou’s subway system and the paralyzing of roadways, which resulted in dozens of deaths, on the historic nature of the rains, which they called a “once in a thousand years” event.

A hospital atrium was flooded in Zhengzhou, Henan province, last month.

A hospital atrium was flooded in Zhengzhou, Henan province, last month.

Photo: Yao Junyi/Zuma Press

Chinese state media have released stories praising the heroism of rescue workers, while articles criticizing the local government’s actions have quickly disappeared from the internet.

As Zhengzhou recovers from the damage, the city will also have to grapple with an outbreak of Covid-19 as the highly infectious Delta variant quickly spreads across the country.

Since a cluster was first detected in the eastern Chinese city of Nanjing last month—the same day Zhengzhou was hit by intense floods—the cluster has grown to more than 250 cases spread over at least 26 cities. According to Henan’s health commission, the province saw more than 60 new cases over the weekend, though local authorities are still tracing the origin of the province’s latest outbreak.

—Lekai Liu contributed to this article.

Write to Eva Xiao at eva.xiao@wsj.com

Corrections & Amplifications
The number of Zhengzhou residents who died when houses collapsed during the floods is 54. An earlier version of this article incorrectly said 50 had died. (Corrected on Aug. 2, 2021)