Police are looking into the cause of a mine collapse that trapped two miners and the mining company's response.

The two miners, who were trapped underground when a zinc mine collapsed in Bonghwa, North Gyeongsang Province, were rescued Friday night.

The Gyeongbuk Provincial Police announced Saturday that it had organized an investigation team dedicated to the Bonghwa mine collapse, consisting of 18 investigators. The focus of the investigation will be on how and why the company did not report the accident immediately, and whether laws were broken.

The company was already under investigation on suspicion of professional negligence resulting in one death and one injury after a similar collapse on Aug. 29, a police official said.

The accident occurred around 6 p.m. on Oct. 26, when about 900 tons of soil poured into the mine. Among seven miners who were working at the time, two escaped in advance after sensing danger, and three were trapped but were rescued at around 11 p.m. through the company's own rescue operation.

The company continued rescue efforts, but failed to reach the two remaining workers. They reported the accident to the fire authorities at 8:34 a.m. Oct. 27, 14 hours after the accident.

Fire authorities' rescue efforts began immediately, but they used outdated blueprints that the company provided. On Oct. 31, rescue authorities admitted that the drilling, which lasted about 32 hours, was conducted in the wrong location and began searching for new coordinates.

Fire authorities announced that they had successfully rescued the miners, aged 62 and 56, at around 11:03 on Friday, 221 hours after the initial incident. Both survivors walked out of the mine on foot, and the Andong Medical Group Hospital confirmed they were in a relatively healthy state.

The two miners reportedly made tents of vinyl and wood at their evacuation sites to avoid drafts and maintain body temperature. The coffee mix they had at the time of the accident also helped them survive.

Politicians including the president and labor minister congratulated and thanked the two miners for their safe return.

President Yoon Suk-yeol send cards and gifts to the two miners on Saturday afternoon, according to a written briefing Sunday. The message in the cards reads "You gave a new hope to the grieving country. I hope for your fast recovery," an apparent reference to the Itaewon disaster.

Minister of Employment and Labor Lee Jung-sik also expressed his gratitude to mine and rescue workers for their efforts through social media Saturday.