The death toll from a powerful earthquake in southwestern Japan rose to 34 on Friday as rescue crews continued a desperate search for survivors after the quake triggered a shopping 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 running water. Thousands of residents remained in evacuation shelters or slept in their vehicles, raising concerns among health officials about heat-related illnesses as the region endured intense summer temperatures.

The magnitude 7.1 earthquake struck Japan's southern main island of Kyushu on Tuesday. As search efforts entered a fourth day, authorities had yet to determine how many people remained missing, while the full extent of the damage to homes and infrastructure was still being assessed.

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

More than 79,000 households remained without running water and more than 2,700 were still without electricity as of Friday afternoon. Authorities said more than 9,000 people were staying in evacuation shelters, where additional power sources were being installed to provide air conditioning. Officials hoped to restore electricity to most affected homes by Friday evening.

Fuel also became scarce as power outages disabled gas stations and quake damage disrupted deliveries from other regions. Many people resorted to sleeping in their cars but, because of the fuel shortage, struggled to keep the air conditioning running in sweltering temperatures.

Temperatures were forecast to reach 36 degrees Celsius (97 degrees Fahrenheit) in Kumamoto on Friday, according to the Japan Meteorological Agency, after reaching 35 degrees Celsius (95 degrees Fahrenheit) on Thursday.

Kumamoto is also a major industrial hub, and there are concerns the quake could disrupt semiconductor and auto parts supply chains for months.

Taiwan Semiconductor Manufacturing Co., a global chip giant that operates a fabrication plant in Kumamoto, said it temporarily evacuated workers after the facility experienced strong shaking from the earthquake. The company said all personnel were safe and operations were gradually resuming after post-quake inspections found the structure was sound, although detailed inspections and impact assessments were still underway.

Japanese officials said Friday afternoon was a crucial period for rescue efforts because experts say the chances of survival 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 severe damage was recorded. The complex was bustling with thousands of people when the earthquake struck.

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

At the site, seven people were confirmed dead and 11 were rescued, Chief Cabinet Secretary Minoru Kihara told reporters in Tokyo on Friday. Authorities did not say how many people were still missing.

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

Smaller-scale searches continued Friday at the sites of collapsed homes in hard-hit towns across southern Kumamoto. Authorities have not provided a firm figure for the number of people still missing.

Shinkansen bullet train service resumed between Kumamoto and Fukuoka to the north, though with reduced service, according to Kyushu Railway Co. Services connecting cities farther south to Kagoshima remained suspended.

Local train services in quake-hit areas, mainly in southern Kumamoto, also remained suspended because of earthquake damage.

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

Some were without water or electricity, while others were too afraid 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 after a powerful earthquake struck Kumamoto in 2016.

"It's exhausting," she said. "We've been sleep-deprived in the car."