Rescue teams searched through a collapsed shopping mall and homes Wednesday after a powerful earthquake killed at least 13 and left many missing in southwestern Japan.

Bullet train services and some airport operations remained suspended and damage was still being assessed a day after the magnitude 7.1 earthquake struck the Kumamoto area on the southern main island of Kyushu.

"There are people who are still waiting to be rescued, and it’s a race against time," Prime Minister Sanae Takaichi said. "We will go all out to find and rescue as many people as we can."

About 36,900 homes were still without electricity, 9,500 homes were without gas and communication networks were not working in some areas, chief government spokesperson Minoru Kihara told reporters.

More than 9,000 people left their homes to stay in more than 500 shelters, and he said power sources were being added so the evacuation centers had air conditioning. Japan has had an ongoing heat wave, and temperatures in the area were forecast to exceed 32 degrees Celsius (90 Fahrenheit).