Passengers queue up for their flights after New Chitose Airport resumed operation in Chitose, Hokkaido, northern Japan, Sept 7, 2018. (KYODO NEWS VIA AP)

TOKYO - New Chitose Airport, the main gateway to Japan's quake-hit Hokkaido prefecture, resumed international flights Saturday morning, as the toll from Thursday quake rose to 21, Japanese government said. 

READ MORE: Japan quake toll rises as rescuers dig through landslides

Six other people are in the state of cardiopulmonary arrest, and 13 people remain missing in the wake of the 6.7-magnitude quake, the government's top spokesperson, Chief Cabinet Secretary Yoshihide Suga told a press conference on Saturday.

Stranded passengers wait for their flights at Chitose airport in Chitose, Hokkaido, northern Japan, Sept 8, 2018. (EUGENE HOSHIKO / AP)

A total of 40,000 people, including local police, firefighters, Self-Defense Force personnel and Japan Coast Guard, are searching for the missing and helping the disaster-hit areas "with all their efforts," said Suga.

According to Japan's transport ministry, about 90 international flights were scheduled to depart from and arrive at the airport near Sapporo during the day.

An earthquake with a preliminary magnitude of 6.7, struck Hokkaido prefecture at 3:08 am local time Thursday.

Rescuers search for missing persons at the site of a landslide triggered by Thursday's earthquake in Atsuma, Hokkaido, northern Japan, Sept 8, 2018. (KYODO NEWS VIA AP)

New Chitose Airport, the main gateway to Hokkaido, was closed throughout Thursday due to damages from the quake as well as a power outage that affected the whole prefecture.

The airport restarted services for domestic flights on Friday, though many passengers were unable to book seats on flights out of Hokkaido due to the masses of people waiting to leave.

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Residents bring out their belongings from an earthquake-damaged house in Kiyota ward of Sapporo, Hokkaido, northern Japan, Sept 8, 2018. (EUGENE HOSHIKO / AP)

At one point after the powerful quake on Thursday, some 2.95 million homes in Hokkaido were without electricity as the whole prefecture suffered a power outage.

Suga said that while power was restored in most of the areas, some 20,000 households were still without electricity, and he urged homes and offices already with power to cut usage by about 10 percent.

According to public broadcaster NHK, as of 6:00 am local time Saturday, some 30,000 households across Hokkaido were still without water supply.

As of 11:00 am local time, some 12,000 people were still taking refuge in more than 430 emergency evacuation shelters across the prefecture, said the public broadcaster.