KUMAMOTO, Japan — The death toll from a powerful earthquake in southwestern Japan rose to 34, the Kumamoto prefectural government said Friday, as rescuers raced in last-ditch efforts to find survivors after the quake triggered a mall explosion, toppled a factory chimney, and flattened homes across the region.

The disaster left thousands of households without electricity and tens of thousands without tap water. Thousands of residents remained in shelters or their vehicles, leaving medical workers concerned about heat-related illnesses as the region endured punishing summer temperatures. The magnitude 7.1 earthquake hit Japan’s southern main island of Kyushu on Tuesday. As search operations entered a fourth day, it wasn’t known how many people remained missing and the scale of the damage to homes across the region was still unclear.

Officials said 34 quake-related deaths had been confirmed, with one more death still under investigation. Dozens of people were injured.

More than 79,000 homes were without water and over 2,700 without electricity as of Friday afternoon. Authorities said more than 9,000 people were staying in shelters, where power sources were being added to provide air conditioning.

Fuel has also become scarce as power outages disabled gas stations and quake damage disrupted deliveries from other regions. Many have resorted to sleeping in their cars, but with the fuel shortage, they struggle to keep the air conditioning running in sweltering temperatures.

Temperatures Friday were due to rise to 36 C (97 F) in Kumamoto city, according to the Japan Meteorological Agency, after stifling 35 C (95 F) heat on Thursday.

Japanese officials say Friday afternoon is a crucial point for rescue efforts as some experts say survival chances decline after the first three days.

Searchers continued to work in the Kumamoto area, including at the site of the collapsed Aeon Mall shopping center in the town of Kashima, where some of the most serious damage was recorded. The complex was bustling with thousands of people when the quake happened.

The company said about 3,000 shoppers were evacuated to a parking lot before an explosion happened in another part of the mall, where some staff remained working. The mall’s second floor collapsed, trapping people.

At the site, seven people were confirmed dead and 11 had been rescued, Japanese Chief Cabinet Sec Minoru Kihara told reporters in Tokyo on Friday. Authorities didn’t say how many were still missing.

Meanwhile, a search operation had ended at a Nippon Paper Industries factory in the Yatsushiro area where a chimney collapsed in the quake, Kihara said. Searchers rescued 11 people there, while nine others were confirmed dead.

Smaller-scale searches continued Friday at the sites of collapsed houses in badly hit towns in southern Kumamoto. Authorities haven’t supplied a firm figure for how many people are missing.

Shinkansen bullet trains resumed between Kumamoto and Fukuoka to the north but with reduced services, according to Kyushu Railway Co., while those connecting cities down south to Kagoshima were still suspended.

Local trains in quake-hit areas, mainly in southern Kumamoto, were still suspended due to quake damage.

In the town of Hikawa, one of the most badly damaged parts of Kumamoto, officials said more than 800 of the town’s 4,500 homes were destroyed or damaged. Many residents slept inside their vehicles in parks, at the town hall parking lot or outside their homes.

Some were without water or electricity, while others were scared to sleep indoors. Among them was Ayako Sudo, a woman in her 70s who was sleeping in her car with her husband.

“Since it’s a wooden house, the shaking is really intense,” Sudo said. “Even when the earthquakes are small, it shakes, and it brings up this feeling of fear. So I think I’d really prefer somewhere that feels safe.”

Sudo slept in her car for two weeks before, after a powerful quake that shook Kumamoto in 2016.

“It’s exhausting,” she said. “We’ve been sleep-deprived in the car.”

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Associated Press senior producer Mayuko Ono in Tokyo contributed to this report.